Problems and Solutions

The early days of life place the developing newborn on the path toward health and success—or not. Fortunately, healthy newborns are the norm, not the exception. However, if something is amiss, it is often part of a cascade that may become overwhelming.

Harmful Substances

Such a cascade begins before the woman realizes she is pregnant, as many toxins, illnesses, and experiences can cause harm early in pregnancy. Every week, scientists discover an unexpected teratogen, which is anything—drugs, viruses, pollutants, malnutrition, stress, and more—that increases the risk of prenatal abnormalities. But do not be alarmed. Many abnormalities can be avoided, many potential teratogens do no harm, and much damage can be remedied. Thus, prenatal life is not a dangerous period to be feared; it is a natural process to be protected.

Some teratogens cause no physical defects but affect the brain, making a child hyperactive, antisocial, or learning-disabled. These are behavioral teratogens. About 20 percent of all children have difficulties that could be connected to behavioral teratogens, although the link is not straightforward: The cascade is murky. One of my students wrote:

Swing High and Low Adopted by loving parents but born with fetal alcohol syndrome, Philip, shown here at age 11, sometimes threatened to kill his family members. His parents sent him to this residential ranch in Eureka, Montana (nonprofit, tuition $3,500 a month) for children like him. This moment during recess is a happy one; it is not known whether he learned to control his fury.

GILES MINGASSON/GETTY IMAGES

As you remember from Chapter 1, one case proves nothing. J. blames her mother, although genes, postnatal experiences, and lack of preventive information and services may be part of the cascade as well. Nonetheless, J. rightly wonders why her mother took a chance.

Behavioral teratogens can be subtle, yet their effects may last a lifetime. That is one conclusion from research on the babies born to pregnant women exposed to flu in 1918. By middle age, although some of these babies grew up to be rich and brilliant, on average those born in flu-ravaged regions had less education, employment, and income than those born a year earlier (Almond, 2006).

Risk Analysis

Life requires risks: We analyze which chances to take and how to minimize harm. To pick an easy example: Crossing the street is risky, yet it would be worse to avoid all street crossing. Knowing the danger, we cross carefully, looking both ways.

Sixty years ago no one analyzed the risks of prenatal development. It was assumed that the placenta screened out all harmful substances. Then two tragic episodes showed otherwise. First, on an Australian military base, an increase in the number of babies born blind was linked to a rubella (German measles) epidemic on the same base seven months earlier (Gregg, 1941; reprinted in Persaud et al., 1985). Second, a sudden rise in British newborns with deformed limbs was traced to maternal use of thalidomide, a new drug for nausea that was widely prescribed in Europe in the late 1950s (Schardein, 1976).

Thus began teratology, a science of risk analysis. Although all teratogens increase the risk of harm, none always cause damage. The impact of teratogens depends on the interplay of many factors, both destructive and protective, an example of the dynamic-systems perspective described in Chapter 1.

Timing is crucial. Some teratogens cause damage only during a critical period (see Figure 4.5). [Lifespan Link: Critical and sensitive periods are described in Chapter 1.] Obstetricians recommend that before pregnancy occurs, women should avoid drugs (especially alcohol), supplement a balanced diet with extra folic acid and iron, and update their immunizations. Indeed, preconception health is at least as important as postconception health (see Table 4.4).

Critical Periods in Human Development The most serious damage from teratogens (green bars) is likely to occur early in prenatal development. However, significant damage (purple bars) to many vital parts of the body, including the brain, eyes, and genitals, can occur during the last months of pregnancy as well.

SOURCE: ADAPTED FROM K. L. MOORE & PERSAUD, 2003

The first days and weeks after conception (the germinal and embryonic periods) are critical for body formation, but health during the entire fetal period affects the brain. Some teratogens that cause preterm birth or low birthweight are particularly harmful in the second half of pregnancy. In fact, one study found that although smoking cigarettes throughout prenatal development can harm the fetus, smokers who quit early in pregnancy had no higher risks of birth complications than did women who never smoked (McCowan et al., 2009).

Timing may be important in another way. When pregnancy occurs soon after a previous pregnancy, risk increases. For example, one study found that second-born children are twice as likely to be autistic if they are born within a year of the firstborn (Cheslac-Postava et al., 2011).

A second factor affecting the harm from teratogens is the dose and/or frequency of exposure. Some teratogens have a threshold effect; they are virtually harmless until exposure reaches a certain level, at which point they “cross the threshold” and become damaging. This threshold is not a fixed boundary: Dose, timing, frequency, and other teratogens affect when the threshold is crossed (O’Leary et al., 2010).

A few substances are beneficial in small amounts but fiercely teratogenic in large quantities. One such substance is vitamin A, which is essential for healthy development but a cause of abnormalities if the dose is 50,000 units per day or higher (obtained only in pills) (Naudé et al., 2007). Experts rarely specify thresholds for any drug, partly because one teratogen may reduce the threshold of another. Alcohol, tobacco, and marijuana are more teratogenic when all three are combined.

Is there a safe amount of psychoactive drugs? Consider alcohol. Early in pregnancy, an embryo exposed to heavy drinking can develop fetal alcohol syndrome (FAS), which distorts the facial features (especially the eyes, ears, and upper lip). Later in pregnancy, alcohol is a behavioral teratogen, leading to hyperactivity, poor concentration, impaired spatial reasoning, and slow learning (Niccols, 2007; Riley et al., 2011).

Some pregnant women, however, drink some alcohol with no evident harm to the fetus. If drinking during pregnancy always caused harm, almost everyone born in Europe before 1980 would be affected. Currently, pregnant women are advised to avoid all alcohol, but women in the United Kingdom receive conflicting advice about drinking a glass of wine a day or two a week (Raymond et al., 2009), and French women are told to abstain but many do not heed that message (Toutain, 2010). Should all women who might become pregnant avoid a legal substance that most men use routinely? Wise? Probably. Necessary?

Genes are a third factor that influences the effects of teratogens. When a woman carrying dizygotic twins drinks alcohol, for example, the twins’ blood alcohol levels are equal; yet one twin may be more severely affected than the other because their alleles for the enzyme that metabolizes alcohol differ. Genetic vulnerability is suspected for many birth defects (Sadler et al., 2010).

The Y chromosome may be crucial in some differential sensitivity. Male fetuses are more likely to be spontaneously aborted or stillborn and also more likely to be harmed by teratogens than female fetuses.

Genes may be important not only at conception but also during pregnancy. One maternal allele results in low levels of folic acid in a woman’s bloodstream and hence in the embryo, which can produce neural-tube defects—either spina bifida, in which the tail of the spine is not enclosed properly (enclosure normally occurs at about week 7), or anencephaly, when part of the brain is missing. Neural-tube defects are more common in certain ethnic groups (Irish, English, and Egyptian), but the crucial maternal allele is rare among Asians and sub-Saharan Africans (Mills et al., 1995).

Since 1998 in the United States, every packaged cereal has added folic acid, an intervention that reduced neural-tube defects by 26 percent in the first three years after the law went into effect (MMWR, September 13, 2002). But some women rarely eat cereal and do not take vitamins. Data by region is not always available, but in 2010 in Appalachia (where many women are of British descent), about 1 newborn in 1,000 had a neural-tube defect.

Applying the Research

Risk analysis cannot precisely predict the results of teratogenic exposure in individual cases. However, much is known more generally about destructive and damaging teratogens and what can be done by individuals and society to reduce the risks. Table 4.5 lists some teratogens and their possible effects, as well as preventive measures.

General health during pregnancy matters. Women are advised to maintain good nutrition and especially to avoid drugs and teratogenic chemicals (which are often found in pesticides, cleaning fluids, and cosmetics). Some medications are necessary (e.g., for women with epilepsy, diabetes, and severe depression), but caution and consultation should begin before pregnancy is confirmed.

Sadly, the cascade of teratogens is most likely to begin with women who are already vulnerable. For example, cigarette smokers are more often drinkers (as was J.’s mother); and those whose jobs require exposure to chemicals and pesticides are more often malnourished (Ahmed & Jaakkola, 2007; Hougaard & Hansen, 2007).

Although prenatal care is helpful in protecting the developing fetus, even doctors are not always careful. One study of 152,000 new mothers in eight U.S. health maintenance organizations (HMOs) found that, during pregnancy, 40 percent of the women were given prescriptions for drugs that had not been declared safe during pregnancy, and 2 percent were prescribed drugs with proven risks to fetuses (Andrade et al., 2004). Perhaps these physicians did not know their patients were pregnant, but even a few of the wrong pills early in pregnancy may do harm.

Worse still is the failure of some doctors to advise women about harmful life patterns. For example, one Maryland study found that almost one-third of pregnant women were not asked about their alcohol use (Cheng et al., 2011). Those who were over age 35 and college-educated were least likely to be queried. Did their doctors assume they knew the dangers? Wrong. In this study, they were also most likely to drink during pregnancy.

Scientists interpret research in contradictory ways. For instance, pregnant women in the United States are told to eat less fish, but those in the United Kingdom are told to increase fish consumption. The reason for these opposite messages is that fish contains both mercury (a teratogen) and DHA (an omega-3 fatty acid needed for fetal brain development) (Oken & Bellinger, 2008; Ramón et al., 2009). Scientists weigh the benefits and risks of fish differently, and few women are able to assess the possible harm from each mouthful, which would require them to know each kind of fish and where it swam.

Another dispute involves bisphenol A (commonly used in plastics), banned in Canada but allowed in the United States. The effect of bisphenol A is disputed because research on mice, not humans, finds it teratogenic. Should people be guided by mouse studies?

Undisputed epidemiological research on humans is logistically difficult because exposure must be measured at several different time points, including early gestation, but the outcome may not manifest itself for many years. No doubt pregnant women are more exposed to bisphenol A than they were a decade ago, and exposure correlates with hyperactive 2-year-olds, but those facts can be interpreted in at least a dozen ways (Braun et al., 2011; Diamanti-Kandarakis et al., 2009).

It is certain that prenatal teratogens can cause behavioral problems, reproductive impairment, and several diseases. Almost every common disease, almost every food additive, most prescription and nonprescription drugs (even caffeine and aspirin), many minerals in the air and water, emotional stress, exhaustion, and poor nutrition might impair prenatal development—but only at some times, in some amounts, in some mammals.

Most research is conducted with mice; harm to humans is rarely proven to everyone’s satisfaction. Even when evidence seems clear, the proper social response is controversial. If a pregnant woman uses alcohol or other psychoactive drugs, should she be jailed for abusing her fetus, as is legal in five U.S. states (Minnesota, North Dakota, Oklahoma, South Dakota, and Wisconsin)? If a baby is stillborn, should the mother be convicted of murder, as occurred for an Oklahoma woman, Theresa Hernandez, who took meth while pregnant and was sentenced to 15 years? (Fentiman, 2009)

Early prenatal care has many benefits: Women learn what to eat, what to do, and what to avoid. Some serious conditions, syphilis and HIV among them, can be diagnosed and treated before any harm to the fetus occurs. In addition, prenatal tests (of blood, urine, and fetal heart rate as well as ultrasound) reassure parents, facilitating the crucial parent-child bond, long before fetal movement is apparent.

In general, early care protects fetal growth, makes birth easier, and renders parents better able to cope. When complications (such as twins, gestational diabetes, and infections) arise, early recognition increases the chance of a healthy birth.

Unfortunately, however, about 20 percent of early pregnancy tests raise anxiety instead of reducing it. For instance, the level of alpha-fetoprotein (AFP) may be too high or too low, or ultrasound may indicate multiple fetuses, abnormal growth, Down syndrome, or a mother’s narrow pelvis. Many such warnings are false positives; that is, they falsely suggest a problem that does not exist. Any warning, whether false or true, requires further testing but also leads to worry and soul-searching. Some choose to abort, some not, with neither option easy. Consider the following.

OPPOSING PERSPECTIVES

“What Do People Live to Do?”

John and Martha, both under age 35, were expecting their second child. Martha’s initial prenatal screening revealed low alpha-fetoprotein, which could indicate Down syndrome.

Happy Boy Martha Beck not only loves her son Adam (shown here), but she also writes about the special experiences he has brought into the whole family’s life—hers, John’s, and their other children’s. She is “pro-choice”; he is a chosen child.

COURTESY KAREN GERDES

Another blood test was scheduled…. John asked:

“What exactly is the problem?”…

“We’ve got a one in eight hundred and ninety-five shot at a retarded baby.”

John smiled, “I can live with those odds.”

“I’m still a little scared.”

He reached across the table for my hand. “Sure,” he said, “that’s understandable. But even if there is a problem, we’ve caught it in time…. The worst-case scenario is that you might have to have an abortion, and that’s a long shot. Everything’s going to be fine.”…

“I might have to have an abortion?” The chill inside me was gone. Instead I could feel my face flushing hot with anger. “Since when do you decide what I have to do with my body?”

John looked surprised. “I never said I was going to decide anything,” he protested. “It’s just that if the tests show something wrong with the baby, of course we’ll abort. We’ve talked about this.”

“What we’ve talked about,” I told John in a low, dangerous voice, “is that I am pro-choice. That means I decide whether or not I’d abort a baby with a birth defect…. I’m not so sure of this.”

“You used to be,” said John.

“I know I used to be.” I rubbed my eyes. I felt terribly confused. “But now…look, John, it’s not as though we’re deciding whether or not to have a baby. We’re deciding what kind of baby we’re willing to accept. If it’s perfect in every way, we keep it. If it doesn’t fit the right specifications, whoosh! Out it goes.”…

John was looking more and more confused. “Martha, why are you on this soapbox? What’s your point?”

“My point is,” I said, “that I’m trying to get you to tell me what you think constitutes a ‘defective’ baby. What about…oh, I don’t know, a hyperactive baby? Or an ugly one?”

“They can’t test for those things and—”

“Well, what if they could?” I said. “Medicine can do all kinds of magical tricks these days. Pretty soon we’re going to be aborting babies because they have the gene for alcoholism, or homosexuality, or manic depression…. Did you know that in China they abort a lot of fetuses just because they’re female?” I growled. “Is being a girl ‘defective’ enough for you? “

“Look,” he said, “I know I can’t always see things from your perspective. And I’m sorry about that. But the way I see it, if a baby is going to be deformed or something, abortion is a way to keep everyone from suffering—especially the baby. It’s like shooting a horse that’s broken its leg…. A lame horse dies slowly, you know?…It dies in terrible pain. And it can’t run anymore. So it can’t enjoy life even if it doesn’t die. Horses live to run; that’s what they do. If a baby is born not being able to do what other people do, I think it’s better not to prolong its suffering.”

“…And what is it,” I said softly, more to myself than to John, “what is it that people do? What do we live to do, the way a horse lives to run?”

[Beck, 1999, pp. 132–133, 135]

The second AFP test was in the normal range, “meaning there was no reason to fear…Down syndrome” (p. 137).

As you read in Chapter 3, genetic counselors help couples discuss their choices before becoming pregnant. John and Martha had had no counseling because the pregnancy was unplanned and their risk for Down syndrome was low. The opposite of a false positive is a false negative, a mistaken assurance that all is well. Amniocentesis later revealed that the second AFP was a false negative. Their fetus had Down syndrome after all. Martha decided against abortion.

Low Birthweight

Some newborns are small and immature. With modern hospital care, tiny infants usually survive, but it would be better for everyone—mother, father, baby, and society—if all newborns were in the womb for at least 35 weeks and weighed more than 2,500 grams (5½ pounds). (Usually, this text gives pounds before grams, but hospitals worldwide report birthweight using the metric system, so grams precede pounds and ounces here.)

The World Health Organization defines low birthweight (LBW) as under 2,500 grams. LBW babies are further grouped into very low birthweight (VLBW), under 1,500 grams (3 pounds, 5 ounces), and extremely low birthweight (ELBW), under 1,000 grams (2 pounds, 3 ounces). Some newborns weigh as little as 500 grams, and they are the most vulnerable—about half of them die even with excellent care (Lau et al., 2013).

Remember that fetal weight normally doubles in the last trimester of pregnancy, with 900 grams (about 2 pounds) of that gain occurring in the final three weeks. Thus, a baby born preterm (three or more weeks early; no longer called premature) is usually, but not always, LBW. Preterm birth correlates with many of the teratogens already mentioned, part of the cascade.

Not every low-birthweight baby is preterm. Some fetuses gain weight slowly throughout pregnancy and are small-for-dates, or small for gestational age (SGA). A full-term baby weighing only 2,600 grams and a 30-week-old fetus weighing only 1,000 grams are both SGA, even though the first is not technically low birthweight. Maternal or fetal illness might cause SGA, but maternal drug use is a more common cause. Every psychoactive drug slows fetal growth, with tobacco implicated in 25 percent of all low-birthweight births worldwide.

Another common reason for slow fetal growth is malnutrition. Women who begin pregnancy underweight, who eat poorly during pregnancy, or who gain less than 3 pounds (1.3 kilograms) per month in the last six months more often have underweight infants.

Unfortunately, many risk factors—underweight, undereating, underage, and smoking—tend to occur together. To make it worse, many such mothers live in poor neighborhoods, where pollution is high—another risk factor for low birthweight (Stieb et al., 2012).

The causes of low birthweight just mentioned rightly focus on the pregnant woman. However, fathers—and grandmothers, neighbors, and communities—are often crucial. As an editorial in a journal for obstetricians explains: “Fathers’ attitudes regarding the pregnancy, fathers’ behaviors during the prenatal period, and the relationship between fathers and mothers…may indirectly influence risk for adverse birth outcomes” (Misra et al., 2010, p. 99).

As already explained in Chapter 1, each person is embedded in a social network. Since the future mother’s behavior impacts the fetus, everyone who affects her also affects the fetus. For instance, unintended pregnancies increase the incidence of low birthweight (Shah et al., 2011). Obviously, intentions are in the mother’s mind, not her body, and they are affected by the father. Thus, the father’s intentions affect her diet, drug use, prenatal care, and so on.

Not only fathers but also the entire social network and culture are crucial (Lewallen, 2011). This is most apparent in what is called the immigrant paradox. Many immigrants have difficulty getting well-paid jobs, and thus are of low socioeconomic status. Low SES correlates with low birthweight. Thus, their newborns should be more often underweight. But, paradoxically, newborns born in the United States to immigrants are generally healthier in every way, including birthweight, than newborns of U.S.-born women of the same gene pool (Coll & Marks, 2012).

This paradox was first recognized among Hispanics, who are the main immigrant group in the U.S., and it was called the Hispanic paradox. Thus, although U.S. residents born in Mexico or South America average lower SES than Hispanics born in the United States, their newborns have fewer problems. Why? Perhaps fathers and grandparents keep pregnant immigrant women drug-free and healthy. The same is now apparent for immigrants from the Caribbean, from Africa, from Eastern Europe, and from Asia compared to U.S.-born women of those ethnicities.

You have already read that life itself is uncertain for the smallest newborns. Ranking worse than most developed nations—and similar to Poland and Malaysia—the U.S. infant mortality rate (death in the first year) is about 6 per 1,000, primarily because of low birthweight.

Moreover, the death rate of the tiniest babies seems to be rising, not falling, even as fewer slightly older newborns die, which is why U.S. infant mortality rates are not falling as fast as they are in other nations (Lau et al., 2013). For survivors who are born very low birthweight, every developmental milestone—smiling, holding a bottle, walking, talking—is later, even when babies are compared on the basis of age since conception, not birth age.

Low-birthweight babies also experience cognitive difficulties as well as visual and hearing impairments. High-risk newborns become infants and children who cry more, pay attention less, disobey, and experience language delays (Aarnoudse-Moens et al., 2009; Spinillo et al., 2009).

Longitudinal research from many nations finds that, in middle childhood, children who were at the extremes of SGA or preterm have many neurological problems, including smaller brain volume, lower IQs, and behavioral difficulties (Hutchinson et al., 2013; van Soelen et al., 2010). Even in adulthood, risks persist: Adults who were LBW are more likely to develop diabetes and heart disease.

Longitudinal data provide both hope and caution. Remember that risk analysis gives odds, not certainties—averages that are not true in every case. By age 4, some ELBW infants are normal in brain development and overall (Claas et al., 2011; Spittle et al., 2009). Those may be the ones who would have been above average if they had stayed in the womb a few more weeks.

In some northern European nations, only 4 percent of newborns weigh under 2,500 grams; in several South Asian nations, more than 20 percent do. Worldwide, far fewer low-birthweight babies are born than two decades ago; as a result, neonatal deaths have been reduced by one-third (Rajaratnam et al., 2010).

Some nations, China and Chile among them, have improved markedly. In 1970, about half of Chinese newborns were LBW; recent estimates put that number at 4 percent (UNICEF, 2010). In some nations, community health programs aid the growth of low-birthweight infants. That makes a notable difference, according to one study provocatively titled Low birth weight outcomes: Why better in Cuba than Alabama? (Neggars & Crowe, 2013).

Getting Better Some public health experts consider the rate of low birthweight to be indicative of national health, since both are affected by the same causes. If that is true, the world is getting healthier, since the LBW world average was 28 percent in 2009 but 16 percent in 2012. When all nations are included, 47 report LBW at 6 per 100 or lower (United States and United Kingdom are not among them).

Source: UNICEF, 2012.

In some nations, notably in sub-Saharan Africa, the LBW rate is rising because global warming, HIV, food shortages, wars, and other problems affect pregnancy. Another nation with troubling rates of LBW rate is the United States, where the rate fell throughout most of the twentieth century, reaching a low of 7.0 percent in 1990. But then it rose again, with the 2010 rate at 8.1 percent, ranging from under 6 percent in Alaska to over 12 percent in Mississippi. The U.S. rate is higher than that of virtually every other developed nation (see Figure 4.6 for a sampling).

Many scientists have developed hypotheses to explain the U.S. rates. One logical possibility is assisted reproduction, since ART often leads to low-birthweight twins and triplets. However, LBW rates rose for naturally conceived babies as well (Pinborg et al., 2004), so ART cannot be the only explanation. Added to the puzzle is the fact that several changes in maternal ethnicity, age, and health since 1990 should have decreased LBW, not increased it.

For example, African Americans have LBW newborns twice as often as the national average (almost 14 percent compared with 7 percent), and younger teenagers have smaller babies than do women in their 20s. However, the birth rate among both groups was much lower in 2010 than it was in 1990. Furthermore, maternal obesity and diabetes are increasing; both lead to heavier babies, not lighter ones.

Something else must be amiss. One possibility is nutrition. Nations with many small newborns are also nations where hunger is prevalent, and increasing hunger correlates with increasing LBW. In both Chile and China, LBW fell as nutrition improved.

As for the United States, the U.S. Department of Agriculture found an increase in food insecurity (measured by skipped meals, use of food stamps, and outright hunger) between 2000 and 2007. Food insecurity directly affects LBW, and it also increases chronic illness, which itself correlates with LBW (Seligman & Schillinger, 2010).

In 2008, about 15 percent of U.S. households were considered food insecure, with rates higher among women in their prime reproductive years than among middle-aged women or men of any age. These rates increased with the economic recession of 2008–2010; if this hypothesis is accurate, rates of LBW will continue to increase.

Another possibility is drug use. As you will see in Chapter 16, the rate of smoking, drinking, and other drug use among high school girls reached a low in 1992, then increased, then decreased. Most U.S. women giving birth in the first decade of the 20^th century are in a cohort that experienced rising drug use; they may still suffer the effects. If that is the reason, the recent decrease in drug use among teenagers will result in fewer LBW in the second decade of the 21st century. Sadly, in developing nations, more young women are smoking and drinking than a decade ago, including in China. Will rates rise in China soon?

A third possibility is pollution. Air pollution is increasing in China, but decreasing in the United States. If pollution is the cause, low birth rate in those nations may change in the next decade. Looking at trends in various nations will help developmentalists understand how to prevent LBW in the future.

Complications During Birth

Any birth complication usually has multiple causes: a fetus is low birthweight, preterm, or exposed to teratogens and a mother is unusually young, old, small, or ill. As an example, cerebral palsy (a disease marked by difficulties with movement) was once thought to be caused solely by birth procedures (excessive medication, slow breech birth, or use of forceps to pull the fetal head through the birth canal). However, we now know that cerebral palsy results from genetic vulnerability, teratogens, and maternal infection (J. R. Mann et al., 2009), worsened by insufficient oxygen to the fetal brain at birth.

A lack of oxygen is anoxia. Anoxia often occurs for a second or two during birth, indicated by a slower fetal heart rate, with no harm done. To prevent prolonged anoxia, the fetal heart rate is monitored during labor and the Apgar is used immediately after birth. How long anoxia can continue without harming the brain depends on genes, birthweight, gestational age, drugs in the bloodstream (either taken by the mother before birth or given during birth), and many other factors. Thus, anoxia is part of a cascade that may cause cerebral palsy. The same cascade applies to almost every other birth complication.