EAR 20 CHAPTER 4 PRENATAL DEVELOPMENT

How do doctors protect the fetus, and when might a doctor do harm?

Although prenatal care is helpful in protecting the developing fetus, even doctors are not always careful. One concern is pain medication. Opioids (narcotics) may do damage to the fetus and aspirin may cause excessive bleeding during birth. Yet a recent study found that 23 percent of pregnant women on Medicaid are given a prescription for a narcotic. Worse still is that some doctors do not ask 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. Those who were over age 35 and college educated were least likely to be queried.

How do anoxia and cerebral palsy illustrate the need for risk analysis?

Any birth complication usually has multiple causes, which is why risk analysis is crucial. 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 sensitivity, teratogens, and maternal infection worsened by insufficient oxygen to the fetal brain at birth. In another example, lack of oxygen can cause 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. Again; however, anoxia is only part of a cascade. 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 of factors that may cause cerebral palsy.

What impact do fathers have during and after birth?

At birth, the father's presence reduces complications, in part because his presence helps the mother during the birthing process. After birth, a father's support of the new family is crucial, sometimes being the reason for a healthy, happy newborn and mother. From a developmental perspective, some causes of postpartum depression (such as financial stress or marital problems) predate the pregnancy; others occur during pregnancy (especially if the woman is worried about the fetus or birth process); others correlate with birth (especially if the mother is unprepared, alone, or surrounded with unsupportive medical professionals); and still others are specific to the particular infant (health, feeding, or sleeping problems).

Why are developmentalists concerned that surgery is often part of birth?

C-sections are warranted in only about 15 percent of births. While they are generally safe, they are often performed for convenience's sake. However, they result in more complications after birth and reduce breast-feeding. By age 3, children born by cesarean have double the rate of childhood obesity compared to those born vaginally.

Why is it difficult to pin down the impact of behavioral teratogens?

Behavioral teratogens can have subtle effects that may not be apparent or may not impact an individual until later childhood.

What are four reasons a baby might be born LBW?

Being born preterm, maternal or fetal illness, maternal psychoactive drug use, and maternal malnutrition can cause a baby to be born LBW

Why has the rate of cesarean sections increased?

Cesareans make scheduling a baby's delivery easier than the unpredictable vaginal birth, and the actual delivery is quicker than a vaginal birth. Cesareans also carry an added bonus for the hospital since they are quite expensive.

What body parts develop during the period of the embryo?

During the period of the embryo, the brain and spinal column, eyes, ears, nose, and mouth start to form, as do the heart, arms, and legs. This is followed by the upper arm, forearm, palms, webbed fingers, legs, knees, feet, and webbed toes.

What is a specific example of the impact of genes on birth defects?

Genes are 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.

What are the national and international trends in low birthweight?

In some northern European nations, only 4 percent of newborns weigh under 2,500 grams; in several South Asian nations, including India, Pakistan, and the Philippines, 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. Some nations, China and Bangladesh among them, have improved markedly. In 1970, an estimated half of Chinese newborns were LBW; recent estimates put that number at 6 percent. In 1990, half of newborns in Bangladesh were LBW; now the rate is 22 percent. Another nation with a troubling rate of LBW is the United States, where the rate fell throughout most of the twentieth century, reaching a low of 7 percent in 1990. But then it rose again, with the 2012 rate at 7.99 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.

What are the differences among LBW, VLBW, and ELBW?

Low birthweight (LBW) is defined as weight less than 2,500 grams (5 pounds, 8 ounces). LBW babies are further grouped into very low birthweight (VLBW), which is less than 1,500 grams (3 pounds, 5 ounces), and extremely low birthweight (ELBW), which is less than 1,000 grams (2 pounds, 3 ounces).

How do fathers experience pregnancy?

Many fathers experience biological symptoms of pregnancy and birth along with their partners. For example, levels of stress hormones correlate between expectant fathers and mothers. Many fathers experience weight gain and indigestion during pregnancy and pain during labor. Paternal experiences of pregnancy and birth are called couvade.

What are the results of kangaroo care?

Many studies find that kangaroo-care newborns sleep more deeply, gain weight more quickly, and spend more time alert than do infants with standard care. Infants who experience kangaroo care may adjust to life outside the womb better, and parents who use the method may have increased sensitivity and effectiveness in dealing with the newborn's needs.

Why do women choose to have a doula in addition to a midwife or doctor?

Many women have a doula, a person trained to support the laboring woman. Doulas time contractions, use massage, provide encouragement, and do whatever else is helpful. Every comparison study finds that the rate of medical intervention is lower when doulas are part of the birth team. Doulas have proven to be particularly helpful for immigrant, low-income, or unpartnered women who may be intimidated by doctors.

Why are home births more common in some nations than others?

Most U.S. births now take place in hospital labor rooms with high-tech operating rooms nearby in case they are needed. Another 5 percent of U.S. births occur in birthing centers (not in a hospital), and less than 1 percent occur at home (home births are illegal in some jurisdictions). About half of the home births are planned and half not because of unexpectedly rapid labor. The unplanned ones are hazardous if no one is nearby to rescue a newborn in distress. Compared with the United States, planned home births are more common in many other developed nations (2 percent in England, 30 percent in the Netherlands) where midwives are paid by the government. In the Netherlands, special ambulances called flying storks speed mother and newborn to a hospital if needed. Dutch research finds home births better for mothers and no worse for infants than hospital births.

What do newborns do to aid their survival?

Newborns exhibit reflexes that maintain their oxygen supply, body temperature, and manage feeding.

What factors increase or decrease the risk of spina bifida?

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, including spina bifida, in which the tail of the spine is not enclosed properly. 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. Since 1998 in the United States, manufacturers have had to add folic acid to every packaged cereal, an intervention that reduced neural-tube defects by 26 percent in the first three years after the law went into effect. 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

What occurs between the age of viability and full-term development?

Reaching viability simply means that life outside the womb is possible. Many babies born between 22 and 24 weeks die, and survivors born before 27 weeks often develop slowly because they have missed some essential brain development in the uterus. Each day of the final three months improves the odds not only of survival but also of a healthy life and normal cognition. Many aspects of prenatal life are awe-inspiring; the fact that an ordinary woman provides a far better home for a fetus than the most advanced medical technology can attain is one of them.

Why is risk analysis more crucial than targeting any one teratogen?

Risk analysis is crucial throughout human development. For example, pregnancy after age 35 increases the chance of many disorders, but mature parents are more likely to have many assets, psychological as well as material, that benefit their children. Depending on many aspects of the social context, it may be wise to have a baby at age 18 or 42 or any other age. Always, risk analysis is needed; many problems can be prevented or overcome. Although all teratogens increase the risk of harm, none always causes damage; risk analysis involves probabilities, not certainties, and resilient and protective influences are relevant. The impact of teratogens depends on the interplay of many factors, both destructive and constructive.

What are the signs of postpartum depression?

Sometimes the first sign is that the new mother seems euphoric after birth—unable to sleep, stop talking, or keep from worrying. A crash might follow the high. Overwhelmed by sadness and feelings of inadequacy, a mother suffering from postpartum depression may have trouble caring for her newborn

How has the Apgar scale increased newborns' survival rate?

The Apgar scale alerts doctors to the condition of a newborn who needs medical attention.

How might the father's role be one reason for immigration paradox?

The causes of low birthweight rightly focus on the pregnant woman. However, fathers 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." Not only fathers but also the entire social network and culture are crucial. This is most apparent in what is called the immigrant paradox. Many immigrants have difficulty getting education and well-paid jobs; their socioeconomic status is low. Low SES correlates with low birthweight. Thus, newborns born to immigrants are expected to be underweight. But, paradoxically, they are generally healthier in every way, including birthweight, than newborns of U.S. born women of the same gene pool This paradox was first called the Hispanic paradox because, although U.S. residents born in Mexico or South America average lower SES than people of Hispanic descent born in the United States, their newborns have fewer problems. The same discrepancy has now been demonstrated for immigrants from the Caribbean, Africa, Eastern Europe, and Asia. The crucial factor may be fathers and grandmothers who keep pregnant immigrant women drug-free and healthy, counteracting the stress of poverty.

How does brain development affect survival?

The critical difference between life and death, or between a fragile preterm newborn and a robust one, is maturation of the neurological, respiratory, and cardiovascular systems. As the brain matures, the organs of the body begin to work in harmony. The heart beats faster during activity; fetal movement as well as heart rate quiet down during rest (not necessarily when the mother wants to sleep). In the final prenatal months, the brain not only develops more neurons, but also connects them to each other, destroying neurons that are not functioning. As the body matures, the skin of the skull thickens. That prevents "brain bleeds," one of the hazards of preterm birth in which paper-thin blood vessels in the skull collapse.

How much weight does the fetus gain, and when?

The fetus usually gains at least 4½ pounds (2.1 kilograms) in the third trimester, increasing to an average of about 7½ pounds (about 3.4 kilograms) at birth.

What affects the parent-infant bond?

The parent-infant bond is the strong, loving connection that forms as parents hold, examine, and feed their newborn. It has been claimed that this bond develops in the first hours after birth when a mother touches her naked baby, just as sheep and goats must immediately smell and nuzzle their newborns if they are to nurture them. While research does not find that early skin-to-skin contact is essential for humans, mother-newborn interaction should be encouraged, although the parent-infant bond depends on many factors in addition to birth practices

When are teratogens most harmful to the future baby?

Timing is crucial. Some teratogens cause damage only during a critical period. 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, and thus behavioral teratogens affect the fetus at any time. 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. Another longitudinal study of 7-year-olds found that, although alcohol is a teratogen at every period of pregnancy, binge drinking in the last trimester was more harmful to the brain.

What is the prediction for the future of an ELBW newborn who survives?

When compared with newborns conceived at the same time but born later, low-birthweight (LBW) infants are older when they first smile, hold a bottle, walk, and communicate. As the months go by, cognitive difficulties as well as visual and hearing impairments may emerge. Survivors who were highrisk newborns tend to become infants and children who cry more, pay attention less, disobey, and experience language delays. Even in adulthood, some risks persist. Low-birthweight infants have higher rates of obesity, heart disease, and diabetes. The data provide hope as well as caution: Some LBW infants develop normally, overcoming their early problems if they receive excellent early care in

What are three major developments in the germinal period?

Within hours after conception, the zygote begins duplication and division. After about the 16-cell stage, duplication and division continue and a third process, differentiation, begins. Soon cells specialize, taking different forms and reproducing at various rates, depending on where they are located.