Chapter 3 Prenatal Development, Birth, and the Newborn Baby
An expectant mother reacts with amazement on hearing the robust heartbeat of her nearly full-term fetus. High-quality prenatal care and preparation for the events of childbirth enable her to approach labor and delivery with confidence and excitement.
· ■ SOCIAL ISSUES: HEALTH The Nurse–Family Partnership: Reducing Maternal Stress and Enhancing Child Development Through Social Support
· ■ SOCIAL ISSUES: HEALTH A Cross-National Perspective on Health Care and Other Policies for Parents and Newborn Babies
· ■ BIOLOGY AND ENVIRONMENT The Mysterious Tragedy of Sudden Infant Death Syndrome
When I met Yolanda and Jay one fall in my child development class, Yolanda was just two months pregnant. Approaching age 30, married for several years, and their careers well under way, they had decided to have a baby. To prepare for parenthood, they enrolled in my evening section, arriving once a week after work full of questions: “How does the baby grow before birth?” “When is each organ formed?” “Has its heart begun to beat?” “Can it hear, feel, or sense our presence?”
Most of all, Yolanda and Jay wanted to do everything possible to make sure their baby would be born healthy. Yolanda started to wonder about her diet and whether she should keep up her daily aerobic workout. And she asked me whether an aspirin for a headache, a glass of wine at dinner, or a few cups of coffee during work and study hours might be harmful.
In this chapter, we answer Yolanda and Jay’s questions, along with a great many more that scientists have asked about the events before birth. First, we trace prenatal development, paying special attention to environmental supports for healthy growth, as well as damaging influences that threaten the child’s health and survival. Next, we turn to the events of childbirth. Today, women in industrialized nations have many choices about where and how they give birth, and hospitals go to great lengths to make the arrival of a new baby a rewarding, family-centered event.
Yolanda and Jay’s son Joshua reaped the benefits of his parents’ careful attention to his needs during pregnancy. He was strong, alert, and healthy at birth. Nevertheless, the birth process does not always go smoothly. We will consider the pros and cons of medical interventions, such as pain-relieving drugs and surgical deliveries, designed to ease a difficult birth and protect the health of mother and baby. Our discussion also addresses the development of infants born underweight or too early. We conclude with a close look at the remarkable capacities of newborns.
The sperm and ovum that unite to form the new individual are uniquely suited for the task of reproduction. The ovum is a tiny sphere, measuring 1175 inch in diameter—barely visible to the naked eye as a dot the size of the period at the end of this sentence. But in its microscopic world, it is a giant—the largest cell in the human body. The ovum’s size makes it a perfect target for the much smaller sperm, which measure only 1500 inch.
About once every 28 days, in the middle of a woman’s menstrual cycle, an ovum bursts from one of her ovaries, two walnut-sized organs located deep inside her abdomen, and is drawn into one of two fallopian tubes—long, thin structures that lead to the hollow, soft-lined uterus (see Figure 3.1 ). While the ovum is traveling, the spot on the ovary from which it was released, now called the corpus luteum, secretes hormones that prepare the lining of the uterus to receive a fertilized ovum. If pregnancy does not occur, the corpus luteum shrinks, and the lining of the uterus is discarded two weeks later with menstruation.
The male produces sperm in vast numbers—an average of 300 million a day—in the testes, two glands located in the scrotum, sacs that lie just behind the penis. In the final process of maturation, each sperm develops a tail that permits it to swim long distances, upstream in the female reproductive tract, through the cervix (opening of the uterus) and into the fallopian tube, where fertilization usually takes place. The journey is difficult, and many sperm die. Only 300 to 500 reach the ovum, if one happens to be present. Sperm live for up to 6 days and can lie in wait for the ovum, which survives for only 1 day after being released into the fallopian tube. However, most conceptions result from intercourse occurring during a three-day period—on the day of ovulation or during the 2 days preceding it (Wilcox, Weinberg, & Baird, 1995 ).
With conception, the story of prenatal development begins to unfold. The vast changes that take place during the 38 weeks of pregnancy are usually divided into three phases: (1) the period of the zygote, (2) the period of the embryo, and (3) the period of the fetus. As we look at what happens in each, you may find it useful to refer to Table 3.1 , which summarizes milestones of prenatal development.
Period of the Zygote
FIGURE 3.1 Female reproductive organs, showing fertilization, early cell duplication, and implantation.
(From Before We Are Born, 6th ed., by K. L. Moore & T. V. N. Persaud, p. 87. Copyright © 2003, reprinted with permission from Elsevier, Inc.)
The period of the zygote lasts about two weeks, from fertilization until the tiny mass of cells drifts down and out of the fallopian tube and attaches itself to the wall of the uterus. The zygote’s first cell duplication is long and drawn out; it is not complete until about 30 hours after conception. Gradually, new cells are added at a faster rate. By the fourth day, 60 to 70 cells exist that form a hollow, fluid-filled ball called a blastocyst (refer again to Figure 3.1 ). The cells on the inside, called the embryonic disk, will become the new organism; the outer ring of cells, termed the trophoblast, will become the structures that provide protective covering and nourishment.
TABLE 3.1 Milestones of Prenatal Development
|TRIMESTER||PERIOD||WEEKS||LENGTH AND WEIGHT||MAJOR EVENTS|
|The one-celled zygote multiplies and forms a blastocyst.
The blastocyst burrows into the uterine lining. Structures that feed and protect the developing organism begin to form—amnion, chorion, yolk sac, placenta, and umbilical cord.
|¼ inch (6 mm)
1 inch (2.5 cm); 17ounce (4 g)
|A primitive brain and spinal cord appear. Heart, muscles, ribs, backbone, and digestive tract begin to develop.
Many external body structures (face, arms, legs, toes, fingers) and internal organs form. The sense of touch begins to develop, and the embryo can move.
||9–12||3 inches (7.6 cm); less than 1 ounce (28 g)||Rapid increase in size begins. Nervous system, organs, and muscles become organized and connected, and new behavioral capacities (kicking, thumb sucking, mouth opening, and rehearsal of breathing) appear. External genitals are well-formed, and the fetus’s sex is evident.|
|Second||13–24||12 inches (30 cm); 1.8 pounds (820 g)||The fetus continues to enlarge rapidly. In the middle of this period, fetal movements can be felt by the mother. Vernix and lanugo keep the fetus’s skin from chapping in the amniotic fluid. Most of the brain’s neurons are in place by 24 weeks. Eyes are sensitive to light, and the fetus reacts to sound.|
|Third||25–38||20 inches (50 cm); 7.5 pounds (3,400 g)||The fetus has a good chance of survival if born during this time. Size increases. Lungs mature. Rapid brain development causes sensory and behavioral capacities to expand. In the middle of this period, a layer of fat is added under the skin. Antibodies are transmitted from mother to fetus to protect against disease. Most fetuses rotate into an upside-down position in preparation for birth.|
Source: Moore, Persaud, & Torchia, 2013.
Photos (from top to bottom): © Claude Cortier/Photo Researchers, Inc.; © G. Moscoso/Photo
Researchers, Inc.; © John Watney/Photo Researchers, Inc.; © James Stevenson/Photo Researchers, Inc.; © Lennart Nilsson, A Child Is Born/Scanpix.
Between the seventh and ninth days, implantation occurs: The blastocyst burrows deep into the uterine lining. Surrounded by the woman’s nourishing blood, it starts to grow in earnest. At first, the trophoblast (protective outer layer) multiplies fastest. It forms a membrane, called the amnion , that encloses the developing organism in amniotic fluid, which helps keep the temperature of the prenatal world constant and provides a cushion against any jolts caused by the woman’s movement. A yolk sac emerges that produces blood cells until the liver, spleen, and bone marrow are mature enough to take over this function (Moore, Persaud, & Torchia, 2013 ).
The events of these first two weeks are delicate and uncertain. As many as 30 percent of zygotes do not survive this period. In some, the sperm and ovum do not join properly. In others, cell duplication never begins. By preventing implantation in these cases, nature eliminates most prenatal abnormalities (Sadler, 2010 ).
Period of the zygote: seventh to ninth day. The fertilized ovum duplicates rapidly, forming a hollow ball of cells, or blastocyst, by the fourth day after fertilization. Here the blastocyst, magnified thousands of times, burrows into the uterine lining between the seventh and ninth day.
The Placenta and Umbilical Cord.
By the end of the second week, cells of the trophoblast form another protective membrane—the chorion , which surrounds the amnion. From the chorion, tiny hairlike villi, or blood vessels, emerge. 1 As these villi burrow into the uterine wall, the placenta starts to develop. By bringing the embryo’s and mother’s blood close together, the placenta permits food and oxygen to reach the organism and waste products to be carried away. A membrane forms that allows these substances to be exchanged but prevents the mother’s and embryo’s blood from mixing directly.
The placenta is connected to the developing organism by the umbilical cord , which first appears as a tiny stalk and, during the course of pregnancy, grows to a length of 1 to 3 feet. The umbilical cord contains one large vein that delivers blood loaded with nutrients and two arteries that remove waste products. The force of blood flowing through the cord keeps it firm, so it seldom tangles while the embryo, like a space-walking astronaut, floats freely in its fluid-filled chamber (Moore, Persaud, & Torchia, 2013 ).
By the end of the period of the zygote, the developing organism has found food and shelter. These dramatic beginnings take place before most mothers know they are pregnant.
Period of the Embryo
The period of the embryo lasts from implantation through the eighth week of pregnancy. During these brief six weeks, the most rapid prenatal changes take place as the groundwork is laid for all body structures and internal organs.
Last Half of the First Month.
In the first week of this period, the embryonic disk forms three layers of cells: (1) the ectoderm, which will become the nervous system and skin; (2) the mesoderm, from which will develop the muscles, skeleton, circulatory system, and other internal organs; and (3) the endoderm, which will become the digestive system, lungs, urinary tract, and glands. These three layers give rise to all parts of the body.
At first, the nervous system develops fastest. The ectoderm folds over to form the neural tube , or primitive spinal cord. At 3½ weeks, the top swells to form the brain. While the nervous system is developing, the heart begins to pump blood, and the muscles, backbone, ribs, and digestive tract appear. At the end of the first month, the curled embryo—only ¼ inch long—consists of millions of organized groups of cells with specific functions.
The Second Month.
In the second month, growth continues rapidly. The eyes, ears, nose, jaw, and neck form. Tiny buds become arms, legs, fingers, and toes. Internal organs are more distinct: The intestines grow, the heart develops separate chambers, and the liver and spleen take over production of blood cells so that the yolk sac is no longer needed. Changing body proportions cause the embryo’s posture to become more upright.
Period of the embryo: fourth week. This 4-week-old embryo is only ¼-inch long, but many body structures have begun to form. The primitive tail will disappear by the end of the embryonic period.
Period of the embryo: seventh week. The embryo’s posture is more upright. Body structures—eyes, nose, arms, legs, and internal organs—are more distinct. An embryo this age responds to touch. It can also move, although at less than one inch long and one ounce in weight, it is till too tiny to be felt by the mother.
At 7 weeks, production of neurons (nerve cells that store and transmit information) begins deep inside the neural tube at the astounding pace of more than 250,000 per minute (Nelson, 2011 ). Once formed, neurons begin traveling along tiny threads to their permanent locations, where they will form the major parts of the brain.
At the end of this period, the embryo—about 1 inch long and 17 ounce in weight—can already sense its world. It responds to touch, particularly in the mouth area and on the soles of the feet. And it can move, although its tiny flutters are still too light to be felt by the mother (Moore, Persaud, & Torchia, 2013 ).
Period of the Fetus
The period of the fetus , from the ninth week to the end of pregnancy, is the longest prenatal period. During this “growth and finishing” phase, the organism increases rapidly in size.
The Third Month.
In the third month, the organs, muscles, and nervous system start to become organized and connected. When the brain signals, the fetus kicks, bends its arms, forms a fist, curls its toes, turns its head, opens its mouth, and even sucks its thumb, stretches, and yawns. Body position changes occur as often as 25 times per hour (Einspieler, Marschik, & Prechtl, 2008 ). The tiny lungs begin to expand and contract in an early rehearsal of breathing movements. By the twelfth week, the external genitals are well-formed, and the sex of the fetus can be detected with ultrasound (Sadler, 2010 ). Other finishing touches appear, such as fingernails, toenails, tooth buds, and eyelids. The heartbeat can now be heard through a stethoscope.
Prenatal development is sometimes divided into trimesters , or three equal time periods. At the end of the third month, the first trimester is complete.
The Second Trimester.
By the middle of the second trimester, between 17 and 20 weeks, the new being has grown large enough that the mother can feel its movements. A white, cheeselike substance called vernix protects its skin from chapping during the long months spent bathing in the amniotic fluid. White, downy hair called lanugo also appears over the entire body, helping the vernix stick to the skin.
At the end of the second trimester, many organs are well-developed. And most of the brain’s billions of neurons are in place; few will be produced after this time. However, glial cells, which support and feed the neurons, continue to increase rapidly throughout the remaining months of pregnancy, as well as after birth. Consequently, brain weight increases tenfold from the twentieth week until birth (Roelfsema et al., 2004 ). At the same time, neurons begin forming synapses, or connections, at a rapid pace.
Period of the fetus: eleventh week. The fetus grows rapidly. At 11 weeks, the brain and muscles are better connected. The fetus can kick, bend its arms, and open and close its hands and mouth, and suck its thumb. Notice the yolk sac, which shrinks as the internal organs take over its function of producing blood cells.
Brain growth means new behavioral capacities. The 20-week-old fetus can be stimulated as well as irritated by sounds. And if a doctor looks inside the uterus using fetoscopy (see Table 2.4 on page 56 ), fetuses try to shield their eyes from the light with their hands, indicating that sight has begun to emerge (Moore, Persaud, & Torchia, 2013 ). Still, a fetus born at this time cannot survive. Its lungs are immature, and the brain cannot yet control breathing and body temperature.
The Third Trimester.
During the final trimester, a fetus born early has a chance for survival. The point at which the baby can first survive, called the age of viability , occurs sometime between 22 and 26 weeks (Moore, Persaud, & Torchia, 2013 ). A baby born between the seventh and eighth months, however, usually needs oxygen assistance to breathe. Although the brain’s respiratory center is now mature, tiny air sacs in the lungs are not yet ready to inflate and exchange carbon dioxide for oxygen.
The brain continues to make great strides. The cerebral cortex, the seat of human intelligence, enlarges. As neural connectivity and organization improve, the fetus spends more time awake. At 20 weeks, fetal heart rate reveals no periods of alertness. But by 28 weeks, fetuses are awake about 11 percent of the time, a figure that rises to 16 percent just before birth (DiPietro et al., 1996 ). Between 30 and 34 weeks, fetuses show rhythmic alternations between sleep and wakefulness that gradually increase in organization (Rivkees, 2003 ). Around this time, synchrony between fetal heart rate and motor activity peaks: A rise in heart rate is usually followed within 5 seconds by a burst of motor activity (DiPietro et al., 2006 ). These are clear signs that coordinated neural networks are beginning to form in the brain.
Period of the fetus: twenty-second week. This fetus is almost one foot long and weighs slightly more than one pound. Its movements can be felt easily by the mother and by other family members who place a hand on her abdomen. If born now, the fetus has a slim chance of surviving.
By the end of pregnancy, the fetus also takes on the beginnings of a personality. Fetal activity is linked to infant temperament. In one study, more active fetuses during the third trimester became 1-year-olds who could better handle frustration and 2-year-olds who were less fearful, in that they more readily interacted with toys and with an unfamiliar adult in a laboratory (DiPietro et al., 2002 ). Perhaps fetal activity is an indicator of healthy neurological development, which fosters adaptability in childhood. The relationships just described, however, are only modest. As we will see in Chapter 6 , sensitive caregiving can modify the temperaments of children who have difficulty adapting to new experiences.
Period of the fetus: thirty-sixth week. This fetus fills the uterus. To nourish it, the umbilical cord and placenta have grown large. Notice the vernix (a cheeselike substance) on the skin, which protects it from chapping. The fetus has accumulated fat to aid temperature regulation after birth. In two more weeks, it will be full-term.
The third trimester brings greater responsiveness to stimulation. Between 23 and 30 weeks, connections form between the cerebral cortex and brain regions involved in pain sensitivity. By this time, painkillers should be used in any surgical procedures (Lee et al., 2005 ). Around 28 weeks, fetuses blink their eyes in reaction to nearby sounds (Kisilevsky & Low, 1998 ; Saffran, Werker, & Werner, 2006 ). And at 30 weeks, fetuses presented with a repeated auditory stimulus against the mother’s abdomen initially react with a rise in heart rate and body movements. But over the next 5 to 6 minutes, responsiveness gradually declines, indicating habituation (adaptation) to the sound. If the stimulus is reintroduced after a 10-minute delay, heart rate falls off far more quickly (Dirix et al., 2009 ). This suggests that fetuses can remember for at least a brief period.
Within the next six weeks, fetuses distinguish the tone and rhythm of different voices and sounds. They show systematic heart rate changes to a male versus a female speaker, to the mother’s voice versus a stranger’s, to a stranger speaking their native language (English) versus a foreign language (Mandarin Chinese), and to a simple familiar melody (descending tones) versus an unfamiliar melody (ascending tones) (Granier-Deferre et al., 2003 ; Huotilainen et al., 2005 ; Kisilevsky et al., 2003 , 2009 ; Lecanuet et al., 1993 ). And in one clever study, mothers read aloud Dr. Seuss’s lively book The Cat in the Hat for the last six weeks of pregnancy. After birth, their infants learned to turn on recordings of the mother’s voice by sucking on nipples. They sucked hardest to hear The Cat in the Hat—the sound they had come to know while still in the womb (DeCasper & Spence, 1988).
In the final three months, the fetus gains more than 5 pounds and grows 7 inches. In the eighth month, a layer of fat is added to assist with temperature regulation. The fetus also receives antibodies from the mother’s blood that protect against illnesses, since the newborn’s own immune system will not work well until several months after birth. In the last weeks, most fetuses assume an upside-down position, partly because of the shape of the uterus and also because the head is heavier than the feet. Growth slows, and birth is about to take place.
REVIEW Why is the period of the embryo regarded as the most dramatic prenatal period? Why is the period of the fetus called the “growth and finishing” phase?
CONNECT How is brain development related to fetal capacities and behavior?
APPLY Amy, two months pregnant, wonders how the embryo is being fed and what parts of the body have formed. “I don’t look pregnant yet, so does that mean not much development has taken place?” she asks. How would you respond to Amy?
Prenatal Environmental Influences
Although the prenatal environment is far more constant than the world outside the womb, many factors can affect the embryo and fetus. Yolanda and Jay learned that parents—and society as a whole—can do a great deal to create a safe environment for development before birth.
The term teratogen refers to any environmental agent that causes damage during the prenatal period.Scientists chose this label (from the Greek word teras, meaning “malformation” or “monstrosity”) because they first learned about harmful prenatal influences from cases in which babies had been profoundly damaged. But the harm done by teratogens is not always simple and straightforward. It depends on the following factors:
· ● Dose. As we discuss particular teratogens, you will see that larger doses over longer time periods usually have more negative effects.
· ● Heredity. The genetic makeup of the mother and the developing organism plays an important role. Some individuals are better able than others to withstand harmful environments.
· ● Other negative influences. The presence of several negative factors at once, such as additional teratogens, poor nutrition, and lack of medical care, can worsen the impact of a harmful agent.
· ● Age. The effects of teratogens vary with the age of the organism at time of exposure. To understand this last idea, think of the sensitive period concept introduced in Chapter 1 . A sensitive period is a limited time span in which a part of the body or a behavior is biologically prepared to develop rapidly. During that time, it is especially sensitive to its surroundings. If the environment is harmful, then damage occurs, and recovery is difficult and sometimes impossible.
Figure 3.2 on page 86 summarizes prenatal sensitive periods. In the period of the zygote, before implantation, teratogens rarely have any impact. If they do, the tiny mass of cells is usually so damaged that it dies. The embryonic period is the time when serious defects are most likely to occur because the foundations for all body parts are being laid down. During the fetal period, teratogenic damage is usually minor. However, organs such as the brain, ears, eyes, teeth, and genitals can still be strongly affected.
The effects of teratogens go beyond immediate physical damage. Some health effects are delayed and may not show up for decades. Furthermore, psychological consequences may occur indirectly, as a result of physical damage. For example, a defect resulting from drugs the mother took during pregnancy can affect others’ reactions to the child as well as the child’s ability to explore the environment. Over time, parent–child interaction, peer relations, and cognitive, emotional, and social development may suffer. Furthermore, prenatally exposed children may be less resilient in the face of environmental risks, such as single parenthood, parental emotional disturbance, or maladaptive parenting (Yumoto, Jacobson, & Jacobson, 2008 ). As a result, their long-term adjustment may be compromised.
FIGURE 3.2 Sensitive periods in prenatal development.
Each organ or structure has a sensitive period, during which its development may be disturbed. Blue horizontal bars indicate highly sensitive periods. Green horizontal bars indicate periods that are somewhat less sensitive to teratogens, although damage can occur.
(Adapted from Before We Are Born, 7th ed., by K. L. Moore and T. V. N. Persaud, p. 313. Copyright © 2008, reprinted with permission from Elsevier, Inc.)
Notice how an important idea about development discussed in earlier chapters is at work here: bidirectional influences between child and environment. Now let’s look at what scientists have discovered about a variety of teratogens.
Prescription and Nonprescription Drugs.
In the early 1960s, the world learned a tragic lesson about drugs and prenatal development. At that time, a sedative called thalidomide was widely available in Canada, Europe, and South America. When taken by mothers 4 to 6 weeks after conception, thalidomide produced gross deformities of the embryo’s arms and legs and, less frequently, damage to the ears, heart, kidneys, and genitals. About 7,000 infants worldwide were affected (Moore, Persaud, & Torchia, 2013 ). As children exposed to thalidomide grew older, many scored below average in intelligence. Perhaps the drug damaged the central nervous system directly. Or the child-rearing conditions of these severely deformed youngsters may have impaired their intellectual development.
Another medication, a synthetic hormone called diethylstilbestrol (DES), was widely prescribed between 1945 and 1970 to prevent miscarriages. As daughters of these mothers reached adolescence and young adulthood, they showed unusually high rates of cancer of the vagina, malformations of the uterus, and infertility. When they tried to have children, their pregnancies more often resulted in prematurity, low birth weight, and miscarriage than those of non-DES-exposed women. Young men showed an increased risk of genital abnormalities and cancer of the testes (Goodman, Schorge, & Greene, 2011 ; Hammes & Laitman, 2003 ).
Currently, the most widely used potent teratogen is a vitamin A derivative called Accutane (known by the generic name isotretinoin), prescribed to treat severe acne and taken by hundreds of thousands of women of childbearing age in industrialized nations. Exposure during the first trimester results in eye, ear, skull, brain, heart, and immune system abnormalities (Honein, Paulozzi, & Erickson, 2001 ). Accutane’s packaging warns users to avoid pregnancy by using two methods of birth control, but many women do not heed this advice (Garcia-Bournissen et al., 2008 ).
Indeed, any drug with a molecule small enough to penetrate the placental barrier can enter the embryonic or fetal bloodstream. Yet many pregnant women continue to take over-the-counter medications without consulting their doctors. Aspirin is one of the most common. Several studies suggest that regular aspirin use is linked to low birth weight, infant death around the time of birth, poorer motor development, and lower intelligence scores in early childhood, although other research fails to confirm these findings (Barr et al., 1990 ; Kozer et al., 2003 ; Streissguth et al., 1987 ). Coffee, tea, cola, and cocoa contain another frequently consumed drug, caffeine. High doses increase the risk of low birth weight (Brent, Christian, & Diener, 2011 ). And persistent intake of antidepressant medication is linked to an elevated incidence of premature delivery and birth complications, including respiratory distress, and to high blood pressure in infancy (Lund, Pedersen, & Henriksen, 2009 ; Roca et al., 2011 ; Udechuku et al., 2010 ).
Because children’s lives are involved, we must take findings like these seriously. At the same time, we cannot be sure that these frequently used drugs actually cause the problems just mentioned. Often mothers take more than one drug. If the embryo or fetus is injured, it is hard to tell which drug might be responsible or whether other factors correlated with drug taking are at fault. Until we have more information, the safest course of action is the one Yolanda took: Avoid these drugs entirely. Unfortunately, many women do not know that they are pregnant during the early weeks of the embryonic period, when exposure to medications (and other teratogens) can be of greatest threat.
The use of highly addictive mood-altering drugs, such as cocaine and heroin, has become more widespread, especially in poverty-stricken inner-city areas, where these drugs provide a temporary escape from a daily life of hopelessness. Nearly 4 percent of U.S. pregnant women take these substances (Substance Abuse and Mental Health Services Administration, 2011 ).
Babies born to users of cocaine, heroin, or methadone (a less addictive drug used to wean people away from heroin) are at risk for a wide variety of problems, including prematurity, low birth weight, physical defects, breathing difficulties, and death around the time of birth (Bandstra et al., 2010 ; Howell, Coles, & Kable, 2008 ; Schuetze & Eiden, 2006 ). In addition, these infants are born drug-addicted. They are often feverish and irritable and have trouble sleeping, and their cries are abnormally shrill and piercing—a common symptom among stressed newborns (Bauer et al., 2005 ). When mothers with many problems of their own must care for these babies, who are difficult to calm down, cuddle, and feed, behavior problems are likely to persist.
Throughout the first year, heroin- and methadone-exposed infants are less attentive to the environment than nonexposed babies, and their motor development is slow. After infancy, some children get better, while others remain jittery and inattentive. The kind of parenting they receive may explain why problems persist for some but not for others (Hans & Jeremy, 2001 ).
Evidence on cocaine suggests that some prenatally exposed babies develop lasting difficulties. Cocaine constricts the blood vessels, causing oxygen delivered to the developing organism to fall for 15 minutes following a high dose. It also can alter the production and functioning of neurons and the chemical balance in the fetus’s brain. These effects may contribute to an array of cocaine-associated physical defects, including eye, bone, genital, urinary tract, kidney, and heart deformities; brain hemorrhages and seizures; and severe growth retardation (Covington et al., 2002 ; Feng, 2005 ; Salisbury et al., 2009 ). Several studies report perceptual, motor, attention, memory, language, and impulse-control problems that persist into the preschool and school years (Bandstra et al., 2011 ; Dennis et al., 2006 ; Lester & Lagasse, 2010 ; Linares et al., 2006 ).
This infant, born many weeks before his due date, breathes with the aid of a respirator. Prematurity and low birth weight can result from a variety of environmental influences during pregnancy, including maternal drug and tobacco use.
Other investigations, however, reveal no major negative effects of prenatal cocaine exposure (Behnke et al., 2006 ; Frank et al., 2005 ; Hurt et al., 2009 ). These contradictory findings indicate how difficult it is to isolate the precise damage caused by illegal drugs. Cocaine users vary greatly in the amount, potency, and purity of the cocaine they ingest. Also, they often take several drugs, display other high-risk behaviors, suffer from poverty and other stresses, and engage in insensitive caregiving—factors that worsen outcomes for children (Jones, 2006 ). But researchers have yet to determine exactly what accounts for findings of cocaine-related damage in some studies but not in others.
Another illegal drug, marijuana, is used more widely than heroin and cocaine. Researchers have linked prenatal marijuana exposure to smaller head size (a measure of brain growth); attention, memory, and academic achievement difficulties; impulsivity and overactivity; and depression as well as anger and aggression in childhood and adolescence (Goldschmidt et al., 2004 ; Gray et al., 2005 ; Huizink & Mulder, 2006 ; Jutras-Aswad et al., 2009 ). As with cocaine, however, lasting consequences are not well-established. Overall, the effects of illegal drugs are far less consistent than the impact of two legal substances to which we now turn: tobacco and alcohol.
Although smoking has declined in Western nations, an estimated 14 percent of U.S. women smoke during their pregnancies (Tong et al., 2009 ). The best-known effect of smoking during the prenatal period is low birth weight. But the likelihood of other serious consequences, such as miscarriage, prematurity, cleft lip and palate, blood vessel abnormalities, impaired heart rate and breathing during sleep, infant death, and asthma and cancer later in childhood, also increases (Geerts et al., 2012 ; Howell, Coles, & Kable, 2008 ; Jaakkola & Gissler, 2004 ; Mossey et al., 2009 ). The more cigarettes a mother smokes, the greater the chances that her baby will be affected. And if a pregnant woman stops smoking at any time, even during the third trimester, she reduces the likelihood that her infant will be born underweight and suffer from future problems (Klesges et al., 2001 ).
Even when a baby of a smoking mother appears to be born in good physical condition, slight behavioral abnormalities may threaten the child’s development. Newborns of smoking mothers are less attentive to sounds, display more muscle tension, are more excitable when touched and visually stimulated, and more often have colic (persistent crying). These findings suggest subtle negative effects on brain development (Law et al., 2003 ; Sondergaard et al., 2002 ). Consistent with this view, prenatally exposed children and adolescents tend to have shorter attention spans, difficulties with impulsivity and overactivity, poorer memories, lower mental test scores, and higher levels of disruptive, aggressive behavior (Espy et al., 2011 ; Fryer, Crocker, & Mattson, 2008 ; Lindblad & Hjern, 2010 ).
Exactly how can smoking harm the fetus? Nicotine, the addictive substance in tobacco, constricts blood vessels, lessens blood flow to the uterus, and causes the placenta to grow abnormally. This reduces the transfer of nutrients, so the fetus gains weight poorly. Also, nicotine raises the concentration of carbon monoxide in the bloodstreams of both mother and fetus. Carbon monoxide displaces oxygen from red blood cells, damaging the central nervous system and slowing body growth in the fetuses of laboratory animals (Friedman, 1996 ). Similar effects may occur in humans.
From one-third to one-half of nonsmoking pregnant women are “passive smokers” because their husbands, relatives, or co-workers use cigarettes. Passive smoking is also related to low birth weight, infant death, childhood respiratory illnesses, and possible long-term attention, learning, and behavior problems (Best, 2009 ; Pattenden et al., 2006 ). Clearly, expectant mothers should avoid smoke-filled environments.
In his moving book The Broken Cord, Michael Dorris ( 1989 ), a Dartmouth College anthropology professor, described what it was like to rear his adopted son Abel (called Adam in the book), whose biological mother drank heavily throughout pregnancy and died of alcohol poisoning shortly after his birth. A Sioux Indian, Abel was born with fetal alcohol spectrum disorder (FASD) , a term that encompasses a range of physical, mental, and behavioral outcomes caused by prenatal alcohol exposure. Children with FASD are given one of three diagnoses, which vary in severity:
Left photo: This 5-year-old’s mother drank heavily during pregnancy. Her widely spaced eyes, thin upper lip, and flattened philtrum are typical of fetal alcohol syndrome (FAS). Right photo: This 12-year-old has the small head and facial abnormalities of FAS. She also shows the mental impairments and slow growth that accompany the disorder.
· 1. Fetal alcohol syndrome (FAS), distinguished by (a) slow physical growth, (b) a pattern of three facial abnormalities (short eyelid openings; a thin upper lip; a smooth or flattened philtrum, or indentation running from the bottom of the nose to the center of the upper lip), and (c) brain injury, evident in a small head and impairment in at least three areas of functioning—for example, memory, language and communication, attention span and activity level (overactivity), planning and reasoning, motor coordination, or social skills. Other defects—of the eyes, ears, nose, throat, heart, genitals, urinary tract, or immune system—may also be present. Abel was diagnosed as having FAS. As is typical for this disorder, his mother drank heavily throughout pregnancy.
· 2. Partial fetal alcohol syndrome (p-FAS), characterized by (a) two of the three facial abnormalities just mentioned and (b) brain injury, again evident in at least three areas of impaired functioning. Mothers of children with p-FAS generally drank alcohol in smaller quantities, and children’s defects vary with the timing and length of alcohol exposure. Furthermore, recent evidence suggests that paternal alcohol use around the time of conception can alter gene expression (see page 73 in Chapter 2 ), thereby contributing to symptoms (Ouko et al., 2009 ).
· 3. Alcohol-related neurodevelopmental disorder (ARND), in which at least three areas of mental functioning are impaired, despite typical physical growth and absence of facial abnormalities. Again, prenatal alcohol exposure, though confirmed, is less pervasive than in FAS (Chudley et al., 2005 ; Loock et al., 2005 ).
Even when provided with enriched diets, FAS babies fail to catch up in physical size during infancy and childhood. Mental impairment associated with all three FASD diagnoses is also permanent: In his teens and twenties, Abel Dorris had trouble concentrating and keeping a routine job, and he suffered from poor judgment. For example, he would buy something and not wait for change or would wander off in the middle of a task. He died at age 23, after being hit by a car.
The more alcohol a woman consumes during pregnancy, the poorer the child’s motor coordination, speed of information processing, reasoning, and intelligence and achievement test scores during the preschool and school years (Burden, Jacobson, & Jacobson, 2005 ; Korkman, Kettunen, & Autti-Raemoe, 2003 ; Mattson, Calarco, & Lang, 2006 ). In adolescence and early adulthood, FASD is associated with persisting attention and motor-coordination deficits, poor school performance, trouble with the law, inappropriate social and sexual behaviors, alcohol and drug abuse, and lasting mental health problems, including depression and high emotional reactivity to stress (Barr et al., 2006 ; Fryer, Crocker, & Mattson, 2008 ; Hellemans et al., 2010 ; Howell et al., 2006 ; Streissguth et al., 2004 ).
How does alcohol produce its devastating effects? First, it interferes with production and migration of neurons in the primitive neural tube. Brain-imaging research reveals reduced brain size, damage to many brain structures, and abnormalities in brain functioning, including the electrical and chemical activity involved in transferring messages from one part of the brain to another (Coles et al., 2011 ; Haycock, 2009 ). Second, the body uses large quantities of oxygen to metabolize alcohol. A pregnant woman’s heavy drinking draws away oxygen that the developing organism needs for cell growth.
About 25 percent of U.S. mothers report drinking at some time during their pregnancies. As with heroin and cocaine, alcohol abuse is higher in poverty-stricken women. On some Native-American reservations, the incidence of FAS is as high as 10 to 20 percent (Szlemko, Wood, & Thurman, 2006 ; Tong et al., 2009 ). Unfortunately, when affected girls later become pregnant, the poor judgment caused by the syndrome often prevents them from understanding why they themselves should avoid alcohol. Thus, the tragic cycle is likely to be repeated in the next generation.
How much alcohol is safe during pregnancy? Even mild drinking, less than one drink per day, is associated with reduced head size and body growth among children followed into adolescence (Jacobson et al., 2004 ; Martinez-Frias et al., 2004 ). Recall that other factors—both genetic and environmental—can make some fetuses more vulnerable to teratogens. Therefore, no amount of alcohol is safe. Couples planning a pregnancy and expectant mothers should avoid alcohol entirely.
This child’s deformities are linked to radiation exposure early in pregnancy, caused by the Chernobyl nuclear power plant disaster in 1986. She is also at risk for low intelligence and language and emotional disorders.
Defects due to ionizing radiation were tragically apparent in children born to pregnant women who survived the bombing of Hiroshima and Nagasaki during World War II. Similar abnormalities surfaced in the nine months following the 1986 Chernobyl, Ukraine, nuclear power plant accident. After each disaster, the incidence of miscarriage and babies born with underdeveloped brains, physical deformities, and slow physical growth rose dramatically (Double et al., 2011 ; Schull, 2003 ). Evacuation of residents in areas near the Japanese nuclear facility damaged by the March 2011 earthquake and tsunami was intended to prevent these devastating outcomes.
Even when a radiation-exposed baby seems normal, problems may appear later. For example, even low-level radiation, resulting from industrial leakage or medical X-rays, can increase the risk of childhood cancer (Fattibene et al., 1999 ). In middle childhood, prenatally exposed Chernobyl children had abnormal brain-wave activity, lower intelligence test scores, and rates of language and emotional disorders two to three times greater than those of nonexposed Russian children. Furthermore, the more tension parents reported, due to forced evacuation from their homes and worries about living in irradiated areas, the poorer their children’s emotional functioning (Loganovskaja & Loganovsky, 1999 ; Loganovsky et al., 2008 ). Stressful rearing conditions seemed to combine with the damaging effects of prenatal radiation to impair children’s development.
In industrialized nations, an astounding number of potentially dangerous chemicals are released into the environment. More than 75,000 are in common use in the United States, and many new pollutants are introduced each year. When 10 newborns were randomly selected from U.S. hospitals for analysis of umbilical cord blood, researchers uncovered a startling array of industrial contaminants—287 in all (Houlihan et al., 2005 ). They concluded that many babies are “born polluted” by chemicals that not only impair prenatal development but increase the chances of health problems and life-threatening diseases later on.
Certain pollutants cause severe prenatal damage. In the 1950s, an industrial plant released waste containing high levels of mercury into a bay providing seafood and water for the town of Minamata, Japan. Many children born at the time displayed physical deformities, mental retardation, abnormal speech, difficulty in chewing and swallowing, and uncoordinated movements. High levels of prenatal mercury exposure disrupt production and migration of neurons, causing widespread brain damage (Clarkson, Magos, & Myers, 2003 ; Hubbs-Tait et al., 2005 ). Prenatal mercury exposure from maternal seafood diets predicts deficits in speed of cognitive processing and motor, attention, and verbal test performance during the school years (Boucher et al., 2010 ; Debes et al., 2006 ). Pregnant women are wise to avoid eating long-lived predatory fish, such as swordfish, albacore tuna, and shark, which are heavily contaminated with mercury.
For many years, polychlorinated biphenyls (PCBs) were used to insulate electrical equipment until research showed that, like mercury, they entered waterways and the food supply. In Taiwan, prenatal exposure to high levels of PCBs in rice oil resulted in low birth weight, discolored skin, deformities of the gums and nails, brain-wave abnormalities, and delayed cognitive development (Chen & Hsu, 1994 ; Chen et al., 1994 ). Steady, low-level PCB exposure is also harmful. Women who frequently ate PCB-contaminated fish, compared with those who ate little or no fish, had infants with lower birth weights, smaller heads, persisting attention and memory difficulties, and lower intelligence test scores in childhood (Boucher, Muckle, & Bastien, 2009 ; Jacobson & Jacobson, 2003 ; Stewart et al., 2008 ).
Another teratogen, lead, is present in paint flaking off the walls of old buildings and in certain materials used in industrial occupations. High levels of prenatal lead exposure are related to prematurity, low birth weight, brain damage, and a wide variety of physical defects. Even at low levels, affected infants and children show slightly poorer mental and motor development (Bellinger, 2005 ; Jedrychowski et al., 2009 ).
Finally, prenatal exposure to dioxins—toxic compounds resulting from incineration—is linked to brain, immune system, and thyroid damage in babies and to an increased incidence of breast and uterine cancers in women, perhaps through altering hormone levels (ten Tusscher & Koppe, 2004 ). Even tiny amounts of dioxin in the paternal bloodstream cause a dramatic change in sex ratio of offspring: Affected men father nearly twice as many girls as boys (Ishihara et al., 2007 ). Dioxin seems to impair the fertility of Y-bearing sperm prior to conception.
About 5 percent of women in industrialized nations catch an infectious disease while pregnant. Although most of these illnesses, such as the common cold, seem to have no impact, a few—as Table 3.2 illustrates—can cause extensive damage.
In the mid-1960s, a worldwide epidemic of rubella (three-day, or German, measles) led to the birth of more than 20,000 American babies with serious defects and to 13,000 fetal and newborn deaths. Consistent with the sensitive-period concept, the greatest damage occurs when rubella strikes during the embryonic period. More than 50 percent of infants whose mothers become ill during that time show deafness; eye deformities, including cataracts; heart, genital, urinary, intestinal, bone, and dental defects; and mental retardation. Infection during the fetal period is less harmful, but low birth weight, hearing loss, and bone defects may still occur. The organ damage inflicted by prenatal rubella often leads to lifelong health problems, including severe mental illness, diabetes, cardiovascular disease, and thyroid and immune-system dysfunction in adulthood (Brown, 2006 ; Duszak, 2009 ).
Routine vaccination in infancy and childhood has made new rubella outbreaks unlikely in industrialized nations. But an estimated 100,000 cases of prenatal infection continue to occur worldwide, primarily in developing countries in Africa and Asia with weak or absent immunization programs (Bale, 2009 ).
The human immunodeficiency virus (HIV), which can lead to acquired immune deficiency syndrome (AIDS), a disease that destroys the immune system, has infected increasing numbers of women over the past three decades. In developing countries, where 95 percent of new infections occur, more than half affect women. In South Africa, for example, nearly 30 percent of all pregnant women are HIV-positive (South African Department of Health, 2009 ). Untreated HIV-infected expectant mothers pass the deadly virus to the developing organism 20 to 30 percent of the time.
TABLE 3.2 Effects of Some Infectious Diseases During Pregnancy
|DISEASE||MISCARRIAGE||PHYSICAL MALFORMATIONS||MENTAL RETARDATION||LOW BIRTH WEIGHT AND PREMATURITY|
|Acquired immune deficiency syndrome (AIDS)||✗||?||✓||?|
|Herpes simplex 2 (genital herpes)||✓||✓||✓||✓|
|Rubella (German measles)||✓||✓||✓||✓|
✓ = established finding, ✗ = no present evidence, ? = possible effect that is not clearly established.
Sources: Jones, Lopez, & Wilson, 2003; Kliegman et al., 2008; Mardh, 2002; O’Rahilly & Müller, 2001.
AIDS progresses rapidly in infants. By 6 months, weight loss, diarrhea, and repeated respiratory illnesses are common. The virus also causes brain damage, as indicated by seizures, gradual loss in brain weight, and delayed mental and motor development. Nearly half of prenatal AIDS babies die by 1 year of age and 90 percent by age 3 (Devi et al., 2009 ). Antiretroviral drug therapy reduces prenatal AIDS transmission by as much as 95 percent, with no harmful consequences of drug treatment for children. These medications have led to a dramatic decline in prenatally acquired AIDS in Western nations. Although distribution is increasing, antiretroviral drugs are still not widely available in impoverished regions of the world (UNICEF, 2010a ).
As Table 3.2 reveals, the developing organism is especially sensitive to the family of herpes viruses, for which no vaccine or treatment exists. Among these, cytomegalovirus (the most frequent prenatal infection, transmitted through respiratory or sexual contact) and herpes simplex 2 (which is sexually transmitted) are especially dangerous. In both, the virus invades the mother’s genital tract, infecting babies either during pregnancy or at birth.
Babies are tested for the HIV virus in a clinic in Mozambique, Africa. Prenatal treatment with antiretroviral drugs reduces transmission of AIDS from mother to child by as much as 95 percent.
Bacterial and Parasitic Diseases.
Table 3.2 also includes several bacterial and parasitic diseases. Among the most common is toxoplasmosis, caused by a parasite found in many animals. Pregnant women may become infected from eating raw or undercooked meat or from contact with the feces of infected cats. About 40 percent of women who have the disease transmit it to the developing organism. If it strikes during the first trimester, it is likely to cause eye and brain damage. Later infection is linked to mild visual and cognitive impairments (Jones, Lopez, & Wilson, 2003 ). Expectant mothers can avoid toxoplasmosis by making sure that the meat they eat is well-cooked, having pet cats checked for the disease, and turning over the care of litter boxes to other family members.
Other Maternal Factors
Besides avoiding teratogens, expectant parents can support the development of the embryo and fetus in other ways. In healthy, physically fit women, regular moderate exercise, such as walking, swimming, biking, or an aerobic workout, is related to increased birth weight (Olson et al., 2009 ). However, frequent, vigorous exercise, especially late in pregnancy, results in lower birth weight than in healthy, nonexercising controls (Clapp et al., 2002 ; Leet & Flick, 2003 ). Most women, however, do not engage in sufficient moderate exercise during pregnancy to promote their own and their baby’s health (Poudevigne & O’Connor, 2006 ). An expectant mother who remains fit experiences fewer physical discomforts in the final weeks.
In the following sections, we examine other maternal factors—nutrition, emotional stress, blood type, age, and previous births.
During the prenatal period, when children are growing more rapidly than at any other time, they depend totally on the mother for nutrients. A healthy diet that results in a weight gain of 25 to 30 pounds (10 to 13.5 kilograms) helps ensure the health of mother and baby.
Prenatal malnutrition can cause serious damage to the central nervous system. The poorer the mother’s diet, the greater the loss in brain weight, especially if malnutrition occurred during the last trimester. During that time, the brain is increasing rapidly in size, and a maternal diet high in all the basic nutrients is necessary for it to reach its full potential. An inadequate diet during pregnancy can also distort the structure of the liver, kidney, pancreas, and other organs, resulting in lifelong health problems, including cardiovascular disease and diabetes in adulthood (Barker, 2008 ; Whincup et al., 2008 ).
Because poor nutrition suppresses development of the immune system, prenatally malnourished babies frequently catch respiratory illnesses (Chandra, 1991 ). In addition, they are often irritable and unresponsive to stimulation. In poverty-stricken families, these effects quickly combine with a stressful home life. With age, low intelligence and serious learning problems become more apparent (Pollitt, 1996 ).
Many studies show that providing pregnant women with adequate food has a substantial impact on the health of their newborn babies. Yet the growth demands of the prenatal period require more than just increased quantity of food. Vitamin–mineral enrichment is also crucial. For example, taking a folic acid supplement around the time of conception greatly reduces by more than 70 percent abnormalities of the neural tube, such as anencephaly and spina bifida (see Table 2.4 on page 56 ). Folic acid supplementation early in pregnancy also reduces the risk of other physical defects, including cleft lip and palate, urinary tract abnormalities, and limb deformities. Furthermore, adequate folic acid intake during the last 10 weeks of pregnancy cuts in half the risk of premature delivery and low birth weight (Goh & Koren, 2008 ; MCR Vitamin Study Research Group, 1991 ; Scholl, Hediger, & Belsky, 1996 ).
Because of these findings, U.S. government guidelines recommend that all women of childbearing age consume 0.4 milligrams of folic acid per day. For women who have previously had a pregnancy affected by neural tube defect, the recommended amount is 4 to 5 milligrams (dosage must be carefully monitored, as excessive intake can be harmful) (American Academy of Pediatrics, 2006 ). About half of U.S. pregnancies are unplanned, so government regulations mandate that bread, flour, rice, pasta, and other grain products be fortified with folic acid.
When poor nutrition persists throughout pregnancy, infants usually require more than dietary improvement. Successful interventions must also break the cycle of apathetic mother–baby interactions. Some do so by teaching parents how to interact effectively with their infants, while others focus on stimulating infants to promote active engagement with their physical and social surroundings (Grantham-McGregor et al., 1994 ; Grantham-McGregor, Schofield, & Powell, 1987 ).
Although prenatal malnutrition is highest in poverty-stricken regions of the world, it is not limited to developing countries. The U.S. Special Supplemental Food Program for Women, Infants, and Children (WIC), which provides food packages to low-income pregnant women, reaches about 90 percent of those who qualify because of their extremely low incomes (U.S. Department of Agriculture, 2011b ). But many U.S. women who need nutrition intervention are not eligible for WIC.
When women experience severe emotional stress during pregnancy, their babies are at risk for a wide variety of difficulties. Intense anxiety—especially during the first two trimesters—is associated with higher rates of miscarriage, prematurity, low birth weight, infant respiratory and digestive illnesses, colic (persistent infant crying), sleep disturbances, and irritability during the child’s first three years (Field, 2011 ; Lazinski, Shea, & Steiner, 2008 ; van der Wal, van Eijsden, & Bonsel, 2007 ).
How can maternal stress affect the fetus? TAKE A MOMENT … To understand this process, list the changes you sensed in your own body the last time you were under stress. When we experience fear and anxiety, stress hormones released into our bloodstream—such as epinephrine (adrenaline) and cortisol, known as the “flight or fight” hormones—cause us to be “poised for action.” Large amounts of blood are sent to parts of the body involved in the defensive response—the brain, the heart, and the muscles in the arms, legs, and trunk. Blood flow to other organs, including the uterus, is reduced. As a result, the fetus is deprived of a full supply of oxygen and nutrients.
Maternal stress hormones also cross the placenta, causing a dramatic rise in fetal stress hormones (evident in the amniotic fluid) and, therefore, in fetal heart rate, blood pressure, blood glucose, and activity level (Kinsella & Monk, 2009 ; Weinstock, 2008 ). Excessive fetal stress may permanently alter fetal neurological functioning, thereby heightening stress reactivity in later life. In several studies, infants and children of mothers who experienced severe prenatal anxiety displayed cortisol levels that were either abnormally high or abnormally low, both of which signal reduced physiological capacity to manage stress. Consistent with these findings, such children are more upset than their agemates when faced with novel or challenging experiences—effects that persist into adolescence and early adulthood (Entringer et al., 2009 ; Van den Bergh et al., 2008 ).
Furthermore, maternal emotional stress during pregnancy predicts childhood weakened immune system functioning and increased susceptibility to infectious disease (Nielsen et al., 2011 ). It is also associated with diverse negative behavioral outcomes, including anxiety, short attention span, anger, aggression, overactivity, and lower mental test scores, above and beyond the impact of other risks, such as maternal prenatal maternal smoking, low birth weight, postnatal maternal anxiety, and low SES (de Weerth & Buitelaar, 2005 ; Gutteling et al., 2006 ; Lazinski, Shea, & Steiner, 2008 ; Loomans et al., 2011 ).
But stress-related prenatal complications are greatly reduced when mothers have partners, other family members, and friends who offer social support (Glover, Bergman, & O’Connor, 2008 ). The relationship of social support to positive pregnancy outcomes and subsequent child development is particularly strong for low-income women, who often lead highly stressful lives (see the Social Issues: Health box on page 94 ).
Rh Factor Incompatibility.
When inherited blood types of mother and fetus differ, serious problems sometimes result. The most common cause of these difficulties is Rh factor incompatibility . When the mother is Rh-negative (lacks the Rh blood protein) and the father is Rh-positive (has the protein), the baby may inherit the father’s Rh-positive blood type. If even a little of a fetus’s Rh-positive blood crosses the placenta into the Rh-negative mother’s bloodstream, she begins to form antibodies to the foreign Rh protein. If these enter the fetus’s system, they destroy red blood cells, reducing the oxygen supply to organs and tissues. Mental retardation, miscarriage, heart damage, and infant death can occur.
It takes time for the mother to produce Rh antibodies, so firstborn children are rarely affected. The danger increases with each additional pregnancy. Fortunately, Rh incompatibility can be prevented in most cases. After the birth of each Rh-positive baby, Rh-negative mothers are routinely given a vaccine to prevent the buildup of antibodies.
In Chapter 2 , we noted that women who delay childbearing until their thirties or forties face increased risk of infertility, miscarriage, and babies born with chromosomal defects. Are other pregnancy complications more common for older mothers? Research indicates that healthy women in their thirties have about the same rates as those in their twenties (Bianco et al., 1996 ; Dildy et al., 1996 ; Prysak, Lorenz, & Kisly, 1995 ). Thereafter, as Figure 3.3 reveals, complication rates increase, with a sharp rise among women age 50 to 55—an age at which because of menopause (end of menstruation) and aging reproductive organs, few women can conceive naturally (Salihu et al., 2003 ; Usta & Nassar, 2008 ).
In the case of teenage mothers, does physical immaturity cause prenatal complications? As we will see in Chapter 11 , nature tries to ensure that once a girl can conceive, she is physically ready to carry and give birth to a baby. Infants born to teenagers have a higher rate of problems, but not directly because of maternal age. Most pregnant teenagers come from low-income backgrounds, where stress, poor nutrition, and health problems are common. Also, many are afraid to seek medical care or, in the United States, do not have access to care because they lack health insurance (U.S. Department of Health and Human Services, 2011a ).
FIGURE 3.3 Relationship of maternal age to prenatal and birth complications.
Complications increase after age 40, with a sharp rise between 50 and 55 years. See page 95 for a description of preeclampsia.
(Adapted from Salihu et al., 2003.)
Social Issues: Health The Nurse–Family Partnership: Reducing Maternal Stress and Enhancing Child Development Through Social Support
At age 17, Denise—an unemployed high-school dropout living with her disapproving parents—gave birth to Tara. Having no one to turn to for help during pregnancy and beyond, Denise felt overwhelmed and anxious much of the time. Tara was premature and cried uncontrollably, slept erratically, and suffered from frequent minor illnesses throughout her first year. When she reached school age, she had trouble keeping up academically, and her teachers described her as distractible, unable to sit still, angry, and uncooperative.
The Nurse–Family Partnership, currently implemented in hundreds of counties across 42 U.S. states, is a voluntary home visiting program for first-time, low-income expectant mothers like Denise. Its goals are to reduce pregnancy and birth complications, promote competent early caregiving, and improve family conditions, thereby protecting children from lasting adjustment difficulties. A registered nurse visits the home weekly during the first month after enrollment, twice a month during the remainder of pregnancy and through the middle of the child’s second year, and then monthly until age 2. In these sessions, the nurse provides the mother with intensive social support—a sympathetic ear; assistance in accessing health and other community services and the help of family members (especially fathers and grandmothers); and encouragement to finish high school, find work, and engage in future family planning.
To evaluate the program’s effectiveness, researchers randomly assigned large samples of mothers at risk for high prenatal stress (due to teenage pregnancy, poverty, and other negative life conditions) to nurse-visiting or comparison conditions (just prenatal care, or prenatal care plus infant referral for developmental problems). Families were followed through their child’s school-age years and, in one experiment, into adolescence (Kitzman et al., 2010 ; Olds et al., 2004 , 2007 ; Rubin et al., 2011 ).
As kindergartners, Nurse–Family Partnership children obtained higher language and intelligence test scores. And at both ages 6 and 9, the children of home-visited mothers in the poorest mental health during pregnancy exceeded comparison children in academic achievement and displayed fewer behavior problems. Furthermore, from their baby’s birth on, home-visited mothers were on a more favorable life course: They had fewer subsequent births, longer intervals between their first and second births, more frequent contact with the child’s father, more stable intimate partnerships, less welfare dependence, and a greater sense of control over their lives—key factors in reducing subsequent prenatal stress and in protecting children’s development. Perhaps for these reasons, 12-year-old children of home-visited mothers continued to be advantaged in academic achievement and reported less alcohol use and drug-taking than comparison-group agemates.
Other findings revealed that professional nurses, compared with trained paraprofessionals, were far more effective in preventing outcomes associated with prenatal stress, including high infant fearfulness to novel stimuli and delayed mental development (Olds et al., 2002 ). Nurses were probably more proficient in individualizing program guidelines to fit the strengths and challenges faced by each family. They also might have had unique legitimacy as experts in the eyes of stressed mothers, more easily convincing them to take steps to reduce pregnancy complications that can trigger persisting developmental problems—such as those Tara displayed.
The Nurse–Family Partnership is highly cost-effective (Dawley, Loch, & Bindrich, 2007 ). For $1 spent, it saves more than $5 in public spending on pregnancy complications, preterm births, and child and youth learning and behavior problems.
The Nurse–Family Partnership provides this first-time mother with regular home visits from a registered nurse. In follow-up research, children of home-visited mothers developed more favorably—cognitively, emotionally, and socially—than comparison children.
The Importance of Prenatal Health Care
Yolanda had her first prenatal appointment three weeks after missing her menstrual period. After that, she visited the doctor’s office once a month until she was seven months pregnant, then twice during the eighth month. As birth grew near, Yolanda’s appointments increased to once a week. The doctor kept track of her general health, her weight gain, the capacity of her uterus and cervix to support the fetus, and the fetus’s growth.
Yolanda’s pregnancy, like most others, was free of complications. But unexpected difficulties can arise, especially if mothers have health problems. For example, the 5 percent of pregnant women who have diabetes need careful monitoring. Extra glucose in the diabetic mother’s bloodstream causes the fetus to grow larger than average, making pregnancy and birth problems more common. Maternal high blood glucose also compromises prenatal brain development: It is linked to poorer memory and learning in infancy and early childhood (deRegnier et al., 2007 ). Another complication, experienced by 5 to 10 percent of pregnant women, is preeclampsia (sometimes called toxemia), in which blood pressure increases sharply and the face, hands, and feet swell in the last half of pregnancy. If untreated, preeclampsia can cause convulsions in the mother and fetal death. Usually, hospitalization, bed rest, and drugs can lower blood pressure to a safe level (Vidaeff, Carroll, & Ramin, 2005 ). If not, the baby must be delivered at once.
Unfortunately, 6 percent of pregnant women in the United States wait until after the first trimester to seek prenatal care or receive none at all. Inadequate care is far more common among adolescent and low-income, ethnic-minority mothers. Their infants are three times as likely to be born underweight and five times as likely to die as are babies of mothers who receive early medical attention (Child Trends, 2012 ). Although the poorest of these mothers are eligible for government-sponsored health services, many low-income women do not qualify. As we will see when we take up birth complications, in nations where affordable medical care is universally available, such as Australia, Canada, Japan, and European countries, late-care pregnancies and maternal and infant health problems are greatly reduced.
LOOK AND LISTEN
List prenatal environmental factors that can compromise later academic performance and social adjustment. Ask several adults who hope someday to be parents to explain what they know about each factor. How great is their need for prenatal education?
During a routine prenatal visit, this couple views an ultrasound image of their twins. All pregnant women need regular prenatal care to protect their health and that of their babies.
Besides financial hardship, some mothers have other reasons for not seeking early prenatal care. These include situational barriers (difficulty finding a doctor, getting an appointment, and arranging transportation) and personal barriers (psychological stress, the demands of taking care of other young children, family crises, and ambivalence about the pregnancy). Many also engage in high-risk behaviors, such as smoking and drug abuse, which they do not want to reveal to health professionals (Daniels, Noe, & Mayberry, 2006 ; Maupin et al., 2004 ). These women, who receive little or no prenatal care, are among those who need it most!
Clearly, public education about the importance of early and sustained prenatal care for all pregnant women is badly needed. Refer to Applying What We Know on page 96 , which lists “do’s and don’ts” for a healthy pregnancy, based on our discussion of the prenatal environment.
REVIEW Why is it difficult to determine the prenatal effects of many environmental agents, such as drugs and pollution?
APPLY Nora, pregnant for the first time, believes that a few cigarettes and a glass of wine a day won’t be harmful. Provide Nora with research-based reasons for not smoking or drinking.
REFLECT If you had to choose five environmental influences to publicize in a campaign aimed at promoting healthy prenatal development, which ones would you choose, and why?
Applying What We Know Do’s and Don’ts for a Healthy Pregnancy
|Do make sure that you have been vaccinated against infectious diseases that are dangerous to the embryo and fetus, such as rubella, before you get pregnant. Most vaccinations are not safe during pregnancy.
Do see a doctor as soon as you suspect that you are pregnant, and continue to get regular medical checkups throughout pregnancy.
Do eat a well-balanced diet and take vitamin–mineral supplements, as prescribed by your doctor, both prior to and during pregnancy. Gain 25 to 30 pounds gradually.
Do obtain literature from your doctor, library, or bookstore about prenatal development. Ask your doctor about anything that concerns you.
Do keep physically fit through moderate exercise. If possible, join a special exercise class for expectant mothers.
Do avoid emotional stress. If you are a single expectant mother, find a relative or friend on whom you can rely for emotional support.
Do get plenty of rest. An overtired mother is at risk for pregnancy complications.
Do enroll in a prenatal and childbirth education class with your partner or other companion. When parents know what to expect, the nine months before birth can be one of the most joyful times of life.
|Don’t take any drugs without consulting your doctor.
Don’t smoke. If you have already smoked during part of your pregnancy, cut down or, better yet, quit. If other members of your family smoke, ask them to quit or to smoke outside.
Don’t drink alcohol from the time you decide to get pregnant.
Don’t engage in activities that might expose your embryo or fetus to environmental hazards, such as radiation or chemical pollutants. If you work in an occupation that involves these agents, ask for a safer assignment or a leave of absence.
Don’t engage in activities that might expose your embryo or fetus to harmful infectious diseases, such as toxoplasmosis.
Don’t choose pregnancy as a time to go on a diet.
Don’t gain too much weight during pregnancy. A very large weight gain is associated with complications.
Although Yolanda and Jay completed my course three months before their baby was born, both agreed to return the following spring to share their experiences with my next class. Two-week-old Joshua came along as well. Yolanda and Jay’s story revealed that the birth of a baby is one of the most dramatic and emotional events in human experience. Jay was present throughout Yolanda’s labor and delivery. Yolanda explained:
· By morning, we knew I was in labor. It was Thursday, so we went in for my usual weekly appointment. The doctor said, yes, the baby was on the way, but it would be a while. He told us to go home and relax and come to the hospital in three or four hours. We checked in at 3 in the afternoon; Joshua arrived at 2 o’clock the next morning. When, finally, I was ready to deliver, it went quickly; a half hour or so and some good hard pushes, and there he was! His face was red and puffy, and his head was misshapen, but I thought, “Our son! I can’t believe he’s really here.”
Jay was also elated by Joshua’s birth. “I wanted to support Yolanda and to experience as much as I could. It was awesome, indescribable,” he said, holding Joshua over his shoulder and patting and kissing him gently. In the following sections, we explore the experience of childbirth, from both the parents’ and the baby’s point of view.
The stages of Childbirth
It is not surprising that childbirth is often referred to as labor. It is the hardest physical work a woman may ever do. A complex series of hormonal changes between mother and fetus initiates the process, which naturally divides into three stages (see Figure 3.4 ):
· 1. Dilation and effacement of the cervix. This is the longest stage of labor, lasting an average of 12 to 14 hours with a first birth and 4 to 6 hours with later births. Contractions of the uterus gradually become more frequent and powerful, causing the cervix, or uterine opening, to widen and thin to nothing, forming a clear channel from the uterus into the birth canal, or vagina.
· 2. Delivery of the baby. This stage is much shorter, lasting about 50 minutes for a first birth and 20 minutes in later births. Strong contractions of the uterus continue, but the mother also feels a natural urge to squeeze and push with her abdominal muscles. As she does so with each contraction, she forces the baby down and out.
· 3. Delivery of the placenta. Labor comes to an end with a few final contractions and pushes. These cause the placenta to separate from the wall of the uterus and be delivered in about 5 to 10 minutes.
FIGURE 3.4 The three stages of labor.
The Baby’s Adaptation to Labor and Delivery
At first glance, labor and delivery seem like a dangerous ordeal for the baby. The strong contractions exposed Joshua’s head to a great deal of pressure, and they squeezed the placenta and the umbilical cord repeatedly. Each time, Joshua’s supply of oxygen was temporarily reduced.
Fortunately, healthy babies are well-equipped to withstand these traumas. The force of the contractions causes the infant to produce high levels of stress hormones. Unlike during pregnancy, when excessive stress endangers the fetus, during childbirth high levels of infant cortisol and other stress hormones are adaptive. They help the baby withstand oxygen deprivation by sending a rich supply of blood to the brain and heart (Gluckman, Sizonenko, & Bassett, 1999 ). In addition, stress hormones prepare the baby to breathe by causing the lungs to absorb any remaining fluid and by expanding the bronchial tubes (passages leading to the lungs). Finally, stress hormones arouse the infant into alertness. Joshua was born wide awake, ready to interact with the surrounding world.
The Newborn Baby’s Appearance
Parents are often surprised at the odd-looking newborn—a far cry from the storybook image they may have had in their minds. The average newborn is 20 inches long and 7½ pounds in weight; boys tend to be slightly longer and heavier than girls. The head is large in comparison to the trunk and legs, which are short and bowed. This combination of a large head (with its well-developed brain) and a small body means that human infants learn quickly in the first few months of life. But, unlike most other mammals, they cannot get around on their own until much later.
To accommodate the well-developed brain, a newborn’s head is large in relation to the trunk and legs. This newborn’s body readily turns pink as she takes her first few breaths.
Even though newborn babies may not match parents’ idealized image, some features do make them attractive (Luo, Li, & Lee, 2011 ). Their round faces, chubby cheeks, large foreheads, and big eyes make adults feel like picking them up and cuddling them.
Assessing the Newborn’s Physical Condition: The Apgar Scale
Infants who have difficulty making the transition to life outside the uterus require special help at once. To assess the newborn’s physical condition quickly, doctors and nurses use the Apgar Scale . As Table 3.3 shows, a rating of 0, 1, or 2 on each of five characteristics is made at 1 minute and again at 5 minutes after birth. A combined Apgar score of 7 or better indicates that the infant is in good physical condition. If the score is between 4 and 6, the baby needs assistance in establishing breathing and other vital signs. If the score is 3 or below, the infant is in serious danger and requires emergency medical attention. Two Apgar ratings are given because some babies have trouble adjusting at first but do quite well after a few minutes (Apgar, 1953 ).
Approaches to Childbirth
Childbirth practices, like other aspects of family life, are molded by the society of which mother and baby are a part. In many village and tribal cultures, expectant mothers are well-acquainted with the childbirth process. For example, the Jarara of South America and the Pukapukans of the Pacific Islands treat birth as a vital part of daily life. The Jarara mother gives birth in full view of the entire community, including small children. The Pukapukan girl is so familiar with the events of labor and delivery that she frequently can be seen playing at it. Using a coconut to represent the baby, she stuffs it inside her dress, imitates the mother’s pushing, and lets the nut fall at the proper moment. In most nonindustrialized cultures, women are assisted—though often not by medical personnel—during labor and delivery. Among the Mayans of the Yucatán, the mother leans against the body of a woman called the “head helper,” who supports her weight and breathes with her during each contraction (Jordan, 1993 ; Mead & Newton, 1967 ).
TABLE 3.3 The Apgar scale
|Heart rate||No heartbeat||Under 100 beats per minute||100 to 140 beats per minute|
|Respiratory effort||No breathing for 60 seconds||Irregular, shallow breathing||Strong breathing and crying|
|Reflex irritability (sneezing, coughing, and grimacing)||No response||Weak reflexive response||Strong reflexive response|
|Muscle tone||Completely limp||Weak movements of arms and legs||Strong movements of arms and legs|
|Color b||Blue body, arms, and legs||Body pink with blue arms and legs||Body, arms, and legs completely pink|
a To remember these signs, you may find it helpful to use a technique in which the original labels are reordered and renamed as follows: color = Appearance; heart rate = Pulse; reflex irritability = Grimace; muscle tone = Activity; and respiratory effort = Respiration. Together, the first letters of the new labels spell Apgar.
b The skin tone of nonwhite babies makes it difficult to apply the “pink” color criterion. However, newborns of all races can be rated for pinkish glow resulting from the flow of oxygen through body tissues.
Source: Apgar, 1953.
In Western nations, childbirth has changed dramatically over the centuries. Before the late 1800s, birth usually took place at home and was a family-centered event. The industrial revolution brought greater crowding to cities, along with new health problems. As a result, childbirth moved from home to hospital, where the health of mothers and babies could be protected. Once doctors assumed responsibility for childbirth, women’s knowledge of it declined, and relatives and friends no longer participated (Borst, 1995 ).
In this Peruvian health clinic, families are encouraged to incorporate practices of their village culture into the birth experience. Here, a familiar attendant soothes a new mother as her baby is delivered.
By the 1950s and 1960s, women had begun to question the medical procedures that had come to be used routinely during labor and delivery. Many felt that routine use of strong drugs and delivery instruments had robbed them of a precious experience and was often neither necessary nor safe for the baby. Gradually, a natural childbirth movement arose in Europe and spread to North America. Its purpose was to make hospital birth as comfortable and rewarding for mothers as possible. Today, most hospitals offer birth centers that are family-centered and homelike. Freestanding birth centers, which permit greater maternal control over labor and delivery, including choice of delivery positions, presence of family members and friends, and early contact between parents and baby, also exist. And a small number of North American women reject institutional birth entirely and choose to have their babies at home.
Natural, or Prepared, Childbirth
Yolanda and Jay chose natural , or prepared, childbirth—a group of techniques aimed at reducing pain and medical intervention and making childbirth a rewarding experience. Most natural childbirth programs draw on methods developed by Grantly Dick-Read ( 1959 ) in England and Fernand Lamaze ( 1958 ) in France. These physicians recognized that cultural attitudes had taught women to fear the birth experience. An anxious, frightened woman in labor tenses muscles, turning the mild pain that sometimes accompanies strong contractions into intense pain.
· In a typical natural childbirth program, the expectant mother and a companion (a partner, relative, or friend) participate in three activities:
· ● Classes. Yolanda and Jay attended a series of classes in which they learned about the anatomy and physiology of labor and delivery. Knowledge about the birth process reduces a mother’s fear.
· ● Relaxation and breathing techniques. During each class, Yolanda was taught relaxation and breathing exercises aimed at counteracting the pain of uterine contractions.
· ● Labor coach. Jay learned how to help Yolanda during childbirth by reminding her to relax and breathe, massaging her back, supporting her body, and offering encouragement and affection.
Social support is important to the success of natural childbirth techniques. In Guatemalan and American hospitals that routinely isolated patients during childbirth, some mothers were randomly assigned a doula—a Greek word referring to a trained lay attendant—who stayed with them throughout labor and delivery, talking to them, holding their hands, and rubbing their backs to promote relaxation. These mothers had fewer birth complications, and their labors were several hours shorter than those of women who did not have supportive companionship. Guatemalan mothers who received doula support also interacted more positively with their babies after delivery, talking, smiling, and gently stroking (Kennell et al., 1991 ; Sosa et al., 1980 ).
Other studies indicate that mothers who are supported during labor and delivery—either by a lay birth attendant or by a relative or friend with doula training—less often have cesarean (surgical) deliveries or need medication to control pain. Also, their babies’ Apgar scores are higher, and they are more likely to be breastfeeding at a two-month follow-up (Campbell et al., 2006 , 2007 ; Hodnett et al., 2003 ; McGrath & Kennell, 2008 ). Social support also makes Western hospital-birth customs more acceptable to women from parts of the world where assistance from family and community members is the norm (Dundek, 2006 ).
LOOK AND LISTEN
Talk to several mothers about social supports available to them during labor and delivery. From the mothers’ perspectives, how did those supports (or lack of support) affect the birth experience?
Home birth has always been popular in certain industrialized nations, such as England, the Netherlands, and Sweden. The number of American women choosing to have their babies at home rose during the 1970s and 1980s but remains small, at less than 1 percent (U.S. Department of Health and Human Services, 2011a ). Although some home births are attended by doctors, many more are handled by certified nurse–midwives, who have degrees in nursing and additional training in childbirth management.
After a home birth, the midwife and a lay attendant provide support to the new mother. For healthy women attended by a well-trained doctor or midwife, home birth is as safe as hospital birth.
Is it just as safe to give birth at home as in a hospital? For healthy women who are assisted by a well-trained doctor or midwife, it seems so because complications rarely occur (Fullerton, Navarro, & Young, 2007 ; Wax, Pinette, & Cartin, 2010 ). However, if attendants are not carefully trained and prepared to handle emergencies, the rate of infant death is high (Mehlmadrona & Madrona, 1997 ). When mothers are at risk for any kind of complication, the appropriate place for labor and delivery is the hospital, where life-saving treatment is available.
Four-year-old Melinda walks with a halting, lumbering gait and has difficulty keeping her balance. She has cerebral palsy, a general term for a variety of impairments in muscle coordination caused by brain damage before, during, or just after birth. For about 10 percent of these children, including Melinda, brain damage was caused by anoxia , or inadequate oxygen supply, during labor and delivery (Bracci, Perrone, & Buonocore, 2006 ). Melinda was also in breech position , turned so that the buttocks or feet would be delivered first, and the umbilical cord was wrapped around her neck. Her mother had gotten pregnant accidentally, was frightened and alone, and arrived at the hospital at the last minute. Had she come to the hospital earlier, doctors could have monitored Melinda’s condition and delivered her surgically as soon as squeezing of the umbilical cord led to distress, thereby reducing the damage or preventing it entirely.
In cases like Melinda’s, medical interventions are clearly justified. But in others, they can interfere with delivery and even pose new risks. In the following sections, we examine some commonly used medical procedures during childbirth.
Fetal monitors are electronic instruments that track the baby’s heart rate during labor. An abnormal heartbeat may indicate that the baby is in distress due to anoxia and needs to be delivered immediately. Continuous fetal monitoring, which is required in most U.S. hospitals, is used in over 80 percent of American births (Natale & Dodman, 2003 ). The most popular type of monitor is strapped across the mother’s abdomen throughout labor. A second, more accurate method involves threading a recording device through the cervix and placing it directly under the baby’s scalp.
Fetal monitoring is a safe medical procedure that has saved the lives of many babies in high-risk situations. But in healthy pregnancies, it does not reduce the already low rates of infant brain damage and death (Haws et al., 2009 ). Furthermore, most infants have some heartbeat irregularities during labor, so critics worry that fetal monitors identify many babies as in danger who, in fact, are not. Monitoring is linked to an increase in the number of cesarean (surgical) deliveries, which we will discuss shortly (Thacker & Stroup, 2003 ). In addition, some women complain that the devices are uncomfortable, prevent them from moving easily, and interfere with the normal course of labor.
Still, fetal monitors will probably continue to be used routinely in the United States, even though they are not necessary in most cases. Doctors fear that they will be sued for malpractice if an infant dies or is born with problems and they cannot show that they did everything possible to protect the baby.
Labor and Delivery Medication
Some form of medication is used in more than 80 percent of U.S. births (Althaus & Wax, 2005 ). Analgesics, drugs used to relieve pain, may be given in mild doses during labor to help a mother relax. Anestheticsare a stronger type of painkiller that blocks sensation. Currently, the most common approach to controlling pain during labor is epidural analgesia, in which a regional pain-relieving drug is delivered continuously through a catheter into a small space in the lower spine. Unlike older spinal block procedures, which numb the entire lower half of the body, epidural analgesia limits pain reduction to the pelvic region. Because the mother retains the capacity to feel the pressure of the contractions and to move her trunk and legs, she is able to push during the second stage of labor.
Although pain-relieving drugs help women cope with childbirth and enable doctors to perform essential medical interventions, they also can cause problems. Epidural analgesia, for example, weakens uterine contractions. As a result, labor is prolonged, and the chances of cesarean (surgical) delivery increase (Nguyen et al., 2010 ). And because drugs rapidly cross the placenta, exposed newborns tend to have lower Apgar scores, to be sleepy and withdrawn, to suck poorly during feedings, and to be irritable when awake (Caton et al., 2002 ; Eltzschig, Lieberman, & Camann, 2003 ; Emory, Schlackman, & Fiano, 1996 ). Although no confirmed long-term consequences for development exist, the negative impact of these drugs on the newborn’s adjustment supports the current trend to limit their use.
A cesarean delivery is a surgical birth; the doctor makes an incision in the mother’s abdomen and lifts the baby out of the uterus. Forty years ago, cesarean delivery was rare. Since then, cesarean rates have climbed internationally, reaching 16 percent in Finland, 23 percent in New Zealand, 26 percent in Canada, 30 percent in Australia, and 32 percent in the United States (OECD, 2011b ).
Cesareans have always been warranted by medical emergencies, such as Rh incompatibility, premature separation of the placenta from the uterus, or serious maternal illness or infection (for example, the herpes simplex 2 virus, which can infect the baby during a vaginal delivery). Cesareans are also justified in breech births, in which the baby risks head injury or anoxia (as in Melinda’s case). But the infant’s exact position makes a difference: Certain breech babies fare just as well with a normal delivery as with a cesarean (Giuliani et al., 2002 ). Sometimes the doctor can gently turn the baby into a head-down position during the early part of labor.
Until recently, many women who have had a cesarean have been offered the option of a vaginal birth in subsequent pregnancies. But new evidence indicates that compared with repeated cesareans, a natural labor after a cesarean is associated with slightly increased rates of rupture of the uterus and infant death (Cahill & Macones, 2007 ). As a result, the rule, “Once a cesarean, always a cesarean,” has made a comeback.
Repeated cesareans, however, do not explain the worldwide rise in cesarean deliveries. Instead, medical control over childbirth is largely responsible. Because many needless cesareans are performed, pregnant women should ask questions about the procedure before choosing a doctor. Although the operation itself is safe, mother and baby require more time for recovery. Anesthetic may have crossed the placenta, making cesarean newborns sleepy and unresponsive and at increased risk for breathing difficulties (McDonagh, Osterweil, & Guise, 2005 ).
REVIEW Describe the features and benefits of natural childbirth. What aspect contributes greatly to favorable outcomes, and why?
CONNECT How might use of epidural analgesia negatively affect the parent–newborn relationship? Explain how your answer illustrates bidirectional influences between parent and child, emphasized in ecological systems theory.
APPLY On seeing her newborn baby for the first time, Caroline exclaimed, “Why is she so out of proportion?” What observations prompted Caroline to ask this question? Explain why her baby’s appearance is adaptive.
REFLECT If you were an expectant parent, would you choose home birth? Why or why not?
Preterm and Low-Birth-Weight Infants
Babies born three weeks or more before the end of a full 38-week pregnancy or who weigh less than 5½ pounds (2,500 grams) have for many years been referred to as “premature.” A wealth of research indicates that premature babies are at risk for many problems. Birth weight is the best available predictor of infant survival and healthy development. Many newborns who weigh less than 3½ pounds (1,500 grams) experience difficulties that are not overcome, an effect that becomes stronger as length of pregnancy and birth weight decrease (see Figure 3.5 on page 102 ) (Baron & Rey-Casserly, 2010 ; Bolisetty et al., 2006 ; Dombrowski, Noonan, & Martin, 2007 ). Brain abnormalities, frequent illness, inattention, overactivity, sensory impairments, poor motor coordination, language delays, low intelligence test scores, deficits in school learning, and emotional and behavior problems are some of the difficulties that persist through childhood and ado lescence and into adulthood (Aarnoudse-Moens, Weiglas-Kuperus, & van Goudoever, 2009 ; Clark et al., 2008 ; Delobel-Ayoub et al., 2009 ; Nosarti et al., 2011 ).
About 1 in 13 American infants is born underweight. Although the problem can strike unexpectedly, it occurs especially often among poverty-stricken women (U.S. Department of Health and Human Services, 2011a ). These mothers, as noted earlier, are more likely to be undernourished and to be exposed to other harmful environmental influences. In addition, they often do not receive adequate prenatal care.
Recall from Chapter 2 that prematurity is also common in multiple births. About 60 percent of twins and more than 90 percent of triplets are born early and low birth weight (U.S. Department of Health and Human Services, 2011a ). Because space inside the uterus is restricted, multiples gain less weight than singletons in the second half of pregnancy.
FIGURE 3.5 Rates of infant survival and child disabilities by length of pregnancy.
In a follow-up of more than 2,300 babies born between 23 and 28 weeks gestation, the percentage who survived decreased and the percentage who displayed moderate to severe disabilities (assessed during the preschool years) increased with reduced length of pregnancy. Severe disabilities included cerebral palsy (unlikely to ever walk), severely delayed mental development, deafness, and blindness. Moderate disabilities included cerebral palsy (able to walk with assistance), moderately delayed mental development, and hearing impairments partially correctable with a hearing aid.
(Adapted from Bolisetty et al., 2006.)
Preterm versus Small-for-Date Infants
Although low-birth-weight infants face many obstacles to healthy development, most go on to lead normal lives; about half of those born at 23 to 24 weeks gestation and weighing only a couple of pounds at birth have no disability (refer again to Figure 3.5 ). To better understand why some babies do better than others, researchers divide them into two groups. Preterm infants are those born several weeks or more before their due date. Although they are small, their weight may still be appropriate, based on time spent in the uterus. Small-for-date infants are below their expected weight considering length of the pregnancy. Some small-for-date infants are actually full-term. Others are preterm infants who are especially underweight.
Of the two types of babies, small-for-date infants usually have more serious problems. During the first year, they are more likely to die, catch infections, and show evidence of brain damage. By middle childhood, they are smaller in stature, have lower intelligence test scores, are less attentive, achieve more poorly in school, and are socially immature (Hediger et al., 2002 ; O’Keefe et al., 2003 ; Sullivan et al., 2008 ). Small-for-date infants probably experienced inadequate nutrition before birth. Perhaps their mothers did not eat properly, the placenta did not function normally, or the babies themselves had defects that prevented them from growing as they should. Consequently, small-for-date infants are especially likely to suffer from prenatal neurological impairments that permanently weaken their capacity to manage stress (Wust et al., 2005 ).
Even among preterm newborns whose weight is appropriate for length of pregnancy, just seven more days—from 34 to 35 weeks—greatly reduces rates of illness, costly medical procedures, and lengthy hospital stays (Gladstone & Katz, 2004 ). And despite being relatively low-risk for disabilities, a substantial number of 34-week preterms are below average in physical growth and mildly to moderately delayed in cognitive development in early and middle childhood (Morse et al., 2009 ; Pietz et al., 2004 ; Stephens & Vohr, 2009 ). And in an investigation of over 120,000 New York City births, babies born even 1 or 2 weeks early showed slightly lower reading and math scores at a third-grade follow-up than children who experienced a full-length prenatal period (Noble et al., 2012 ). These outcomes persisted even after controlling for other factors linked to achievement, such as birth weight and SES. Yet doctors often induce births several weeks preterm, under the misconception that these babies are developmentally “mature.”
Consequences for Caregiving
Imagine a scrawny, thin-skinned infant whose body is only a little larger than the size of your hand. You try to play with the baby by stroking and talking softly, but he is sleepy and unresponsive. When you feed him, he sucks poorly. During the short, unpredictable periods in which he is awake, he is usually irritable.
The appearance and behavior of preterm babies can lead parents to be less sensitive in caring for them. Compared with full-term infants, preterm babies—especially those who are very ill at birth—are less often held close, touched, and talked to gently. At times, mothers of these infants resort to interfering pokes and verbal commands in an effort to obtain a higher level of response from the baby (Barratt, Roach, & Leavitt, 1996 ; Feldman, 2007 ). This may explain why preterm babies as a group are at risk for child abuse.
Research reveals that distressed, emotionally reactive preterm infants are especially susceptible to the effects of parenting quality: Among a sample of preterm 9-month-olds, the combination of infant negativity and angry or intrusive parenting yielded the highest rates of behavior problems at 2 years of age. But with warm, sensitive parenting, distressed preterm babies’ rates of behavior problems were the lowest (Poehlmann et al., 2011 ). When they are born to isolated, poverty-stricken mothers who cannot provide good nutrition, health care, and parenting, the likelihood of unfavorable outcomes increases. In contrast, parents with stable life circumstances and social supports usually can overcome the stresses of caring for a preterm infant (Ment et al., 2003). In these cases, even sick preterm babies have a good chance of catching up in development by middle childhood.
These findings suggest that how well preterm infants develop has a great deal to do with the parent–child relationship. Consequently, interventions directed at supporting both sides of this tie are more likely to help these infants recover.
Interventions for Preterm Infants
A preterm baby is cared for in a special Plexiglas-enclosed bed called an isolette. Temperature is carefully controlled because these babies cannot yet regulate their own body temperature effectively. To help protect the baby from infection, air is filtered before it enters the isolette. When a preterm infant is fed through a stomach tube, breathes with the aid of a respirator, and receives medication through an intravenous needle, the isolette can be very isolating indeed! Physical needs that otherwise would lead to close contact and other human stimulation are met mechanically.
Special Infant Stimulation.
In proper doses, certain kinds of stimulation can help preterm infants develop. In some intensive care nurseries, preterm babies can be seen rocking in suspended hammocks or lying on waterbeds designed to replace the gentle motion they would have received while still in the mother’s uterus. Other forms of stimulation have also been used—an attractive mobile or a tape recording of a heartbeat, soft music, or the mother’s voice. These experiences promote faster weight gain, more predictable sleep patterns, and greater alertness (Arnon et al., 2006 ; Marshall-Baker, Lickliter, & Cooper, 1998 ).
Touch is an especially important form of stimulation. In baby animals, touching the skin releases certain brain chemicals that support physical growth—effects believed to occur in humans as well. When preterm infants were massaged several times each day in the hospital, they gained weight faster and, at the end of the first year, were advanced in mental and motor development over preterm babies not given this stimulation (Field, 2001 ; Field, Hernandez-Reif, & Freedman, 2004 ).
In developing countries where hospitalization is not always possible, skin-to-skin “kangaroo care” is the most readily available intervention for promoting the survival and recovery of preterm babies. It involves placing the infant in a vertical position between the mother’s breasts or next to the father’s chest (under the parent’s clothing) so the parent’s body functions as a human incubator. Kangaroo care offers fathers a unique opportunity to increase their involvement in caring for the preterm newborn. Because of its many physical and psychological benefits, the technique is often used in Western nations as a supplement to hospital intensive care.
Kangaroo skin-to-skin contact fosters improved oxygenation of the baby’s body, temperature regulation, sleep, breastfeeding, alertness, and infant survival (Conde-Agudelo, Belizan, & Diaz-Rossello, 2011 ; Lawn et al., 2010 ). In addition, the kangaroo position provides the baby with gentle stimulation of all sensory modalities: hearing (through the parent’s voice), smell (through proximity to the parent’s body), touch (through skin-to-skin contact), and visual (through the upright position). Mothers and fathers practicing kangaroo care feel more confident about caring for their fragile babies and interact more sensitively and affectionately with them (Dodd, 2005 ; Feldman, 2007 ).
Together, these factors may explain why preterm babies given many hours of kangaroo care in their early weeks, compared to those given little or no such care, score higher on measures of mental and motor development during the first year (Charpak, Ruiz-Peláez, & Figueroa, 2005 ; Feldman, 2007 ). Because of its diverse benefits, more than 80 percent of U.S. hospitals now offer kangaroo care to preterm newborns (Field et al., 2006 ).
Top photo: A father in El Salvador uses skin-to-skin “kangaroo care” with his infant as part of a hospital program that teaches parents techniques for promoting survival and development in preterm and underweight babies. Bottom photo: Here, a U.S. mother uses kangaroo care with her fragile newborn.
Training Parents in Infant Caregiving Skills.
Interventions that support parents of preterm infants generally teach them about the infant’s characteristics and promote caregiving skills. For parents with adequate economic and personal resources to care for a preterm infant, just a few sessions of coaching in recognizing and responding to the baby’s needs are linked to enhanced parent–infant interaction, reduced infant crying and improved sleep, more rapid language development in the second year, and steady gains in mental test scores that equal those of full-term children by middle childhood (Achenbach et al., 1990 ; Newnham, Milgrom, & Skouteris, 2009 ).
When preterm infants live in stressed, low-income households, long-term, intensive intervention is required to reduce developmental problems. In the Infant Health and Development Project, preterm babies born into poverty received a comprehensive intervention that combined medical follow-up, weekly parent training sessions, and cognitively stimulating child care from 1 to 3 years of age. More than four times as many intervention children as controls (39 versus 9 percent) were within normal range at age 3 in intelligence, psychological adjustment, and physical growth (Bradley et al., 1994 ). In addition, mothers in the intervention group were more affectionate and more often encouraged play and cognitive mastery in their children—one reason their 3-year-olds may have been developing so favorably (McCarton, 1998 ).
Social Issues: Health A Cross-National Perspective on Health Care and Other Policies for Parents and Newborn Babies
Infant mortality —the number of deaths in the first year of life per 1,000 live births—is an index used around the world to assess the overall health of a nation’s children. Although the United States has the most up-to-date health-care technology in the world, it has made less progress in reducing infant deaths than many other countries. Over the past three decades, it has slipped in the international rankings, from seventh in the 1950s to twenty-eighth in 2012. Members of America’s poor ethnic minorities are at greatest risk. African-American and Native-American babies are nearly twice as likely as white infants to die in the first year of life (U.S. Census Bureau, 2012a , 2012b ).
Neonatal mortality, the rate of death within the first month of life, accounts for 67 percent of the infant death rate in the United States. Two factors are largely responsible for neonatal mortality. The first is serious physical defects, most of which cannot be prevented. The percentage of babies born with physical defects is about the same in all ethnic and income groups. The second leading cause of neonatal mortality is low birth weight, which is largely preventable. African-American and Native-American babies are twice as likely as white infants to be born early and underweight (U.S. Census Bureau, 2012b ).
Widespread poverty and weak health-care programs for mothers and young children are largely responsible for these trends. Each country in Figure 3.6 that outranks the United States in infant survival provides all its citizens with government-sponsored health-care benefits. And each takes extra steps to make sure that pregnant mothers and babies have access to good nutrition, high-quality medical care, and social and economic supports that promote effective parenting.
For example, all Western European nations guarantee women a certain number of prenatal visits at very low or no cost. After a baby is born, a health professional routinely visits the home to provide counseling about infant care and to arrange continuing medical services. Home assistance is especially extensive in the Netherlands. For a token fee, each mother is granted a specially trained maternity helper, who assists with infant care, shopping, housekeeping, meal preparation, and the care of other children during the days after delivery (Zwart, 2007 ).
These fathers in Stockholm take advantage of Sweden’s parental leave program, the most generous in the world, which provides them with two weeks of birth leave followed by 16 months of paid leave at 80 percent of prior earnings.
Paid, job-protected employment leave is another vital societal intervention for new parents. Canadian mothers are eligible for 15 weeks’ maternity leave at 55 percent of prior earnings (up to a maximum of $485 per week), and Canadian mothers or fathers can take an additional 35 weeks of parental leave at the same rate. Paid leave is widely available in other industrialized nations as well. Sweden has the most generous parental leave program in the world. Mothers can begin maternity leave 60 days prior to expected delivery, extending it to six weeks after birth; fathers are granted two weeks of birth leave. In addition, either parent can take full leave for 16 months at 80 percent of prior earnings, followed by an additional three months at a modest flat rate. Each parent is also entitled to another 18 months of unpaid leave. Furthermore, many countries supplement basic paid leave. In Germany, for example, after a fully paid three-month leave, a parent may take one more year at a flat rate and three additional years at no pay (OECD, 2006 ; Waldfogel, 2001 ).
Yet in the United States, the federal government mandates only 12 weeks of unpaid leave for employees in businesses with at least 50 workers. Most women, however, work in smaller businesses, and many of those who work in large enough companies cannot afford to take unpaid leave (Hewlett, 2003 ). Similarly, though paternal leave predicts fathers’ increased involvement in infant care at the end of the first year, many fathers take little or none at all (Nepomnyaschy & Waldfogel, 2007 ; OECD, 2006 ). In 2002, California became the first state to guarantee a mother or father paid leave—up to six weeks at half salary, regardless of the size of the company. Since then, Hawaii, New Jersey, New York, Rhode Island, and the territory of Puerto Rico have passed similar legislation.
Nevertheless, six weeks of childbirth leave (the norm in the United States) is not enough. When a family is stressed by a baby’s arrival, leaves of six weeks or less are linked to increased maternal anxiety, depression, marital dissatisfaction, sense of role overload (conflict between work and family responsibilities), and negative interactions with the baby. A longer leave (12 weeks or more) predicts favorable maternal mental health, supportive marital interaction, and sensitive caregiving (Feldman, Sussman, & Zigler, 2004 ; Hyde et al., 2001 ). Single women and their babies are most hurt by the absence of a generous national paid-leave policy. These mothers, who are usually the sole source of support for their families, can least afford to take time from their jobs.
FIGURE 3.6 Infant mortality in thirty nations.
Despite its advanced health-care technology, the United States ranks poorly. It is twenty-eighth in the world, with a death rate of 6.1 infants per 1,000 births.
(Adapted from U.S. Census Bureau, 2012a.)
In countries with low infant mortality rates, expectant parents need not wonder how or where they will get health care and other resources to support their baby’s development. The powerful impact of universal, high-quality health care, generous parental leave, and other social services on maternal and infant well-being provides strong justification for these policies.
At ages 5 and 8, children who had attended the child-care program regularly—for more than 350 days over the three-year period—continued to show better intellectual functioning. The more they attended, the higher they scored, with greater gains among those whose birth weights were higher—between 4½ and 5½ pounds (2,001 to 2,500 grams). In contrast, children who attended only sporadically gained little or even lost ground (Hill, Brooks-Gunn, & Waldfogel, 2003 ). These findings confirm that babies who are both preterm and economically disadvantaged require intensive intervention. And special strategies, such as extra adult–child interaction, may be necessary to achieve lasting changes in children with the lowest birth weights.
Nevertheless, even the best caregiving environments cannot “fix” the enormous biological risks associated with extremely low birth weight. A better course of action would be to prevent this serious threat to infant survival and development. The high rate of underweight babies in the United States—one of the worst in the industrialized world—could be greatly reduced by improving the health and social conditions described in the Social Issues: Health box above.
Birth Complications, Parenting, and Resilience
In the preceding sections, we considered a variety of birth complications. Now let’s try to put the evidence together. Can any general principles help us understand how infants who survive a traumatic birth are likely to develop? A landmark study carried out in Hawaii provides some answers.
In 1955, Emmy Werner and Ruth Smith began to follow nearly 700 infants on the island of Kauai who had experienced mild, moderate, or severe birth complications. Each was matched, on the basis of SES and ethnicity, with a healthy newborn (Werner & Smith, 1982 ). Findings showed that the likelihood of long-term difficulties increased if birth trauma was severe. But among mildly to moderately stressed children, those growing up in stable families did almost as well on measures of intelligence and psychological adjustment as those with no birth problems. Children exposed to poverty, family disorganization, and mentally ill parents often developed serious learning difficulties, behavior problems, and emotional disturbance.
The Kauai study tells us that as long as birth injuries are not overwhelming, a supportive home environment can restore children’s growth. But the most intriguing cases in this study were the handful of exceptions. A few children with both fairly serious birth complications and troubled family environments grew into competent adults who fared as well as controls in career attainment and psychological adjustment. Werner and Smith found that these children relied on factors outside the family and within themselves to overcome stress. Some had attractive personalities that drew positive responses from relatives, neighbors, and peers. In other instances, a grandparent, aunt, uncle, or babysitter provided the needed emotional support (Werner, 1989 , 2001 ; Werner & Smith,