|Birth Defects Prevention|
Birth defects affect about 120,000 babies born in the United States each year. Birth defects account for more than 20% of infant deaths and contribute substantially to life-long disabilities.
The causes of about 70% of all birth defects are unknown. Various occupational hazards, dietary factors, medications, personal habits, and environmental exposures may contribute to birth defects, but many questions remain about the exact nature of their influence.
Neural tube defects (NTDs) are one of the most common birth defects. NTDs result when the neural tube (which includes the spinal cord and brain) fails to close during the first month of embryonic development. NTDs include several disorders ranging from spina bifida (incomplete closure of the bones around the spinal cord that can lead to paralysis) to a lack of a cranium (the bones of the head) and its contents, called anencephaly. Approximately 4,000 pregnancies in the United States are affected by NTDs each year.
Dietary changes that may be helpful for birth defects prevention
Drinking beverages containing caffeine may increase the risk of miscarriage among non-smoking women, according to one study.1 Women who miscarried during the first 12 weeks of pregnancy were found to have significantly higher consumption of caffeine compared with women who carried their pregnancies to term. This association was limited to women who did not smoke cigarettes. Non-smoking women who consumed 500 mg of caffeine per day, or roughly five cups of coffee, were twice as likely to suffer a miscarriage compared with women who drank less than one cup of coffee per day. An increased risk of miscarriage was also found in women consuming as little of 100 mg of caffeine per day. This finding appears to indicate that there may be no “safe” amount of regular caffeine consumption during pregnancy.
One cup of coffee contains roughly 100 mg of caffeine, depending on how it is brewed (drip coffee contains the most caffeine and instant coffee the least). Black tea contains about 40–70 mg per cup, and a 12-oz. can of caffeinated soda may contain 30–55 mg of caffeine. Caffeine is also found in cocoa, chocolate, and certain over-the-counter medications.
Lifestyle changes that may be helpful for birth defects prevention
Pregnant women should avoid alcohol completely. Alcohol intake by pregnant women can lead to a spectrum of disorders, including fetal alcohol syndrome (FAS), alcohol-related neurodevelopmental disorder (ARND), and alcohol-related birth defects (ARBD). FAS is characterized by growth retardation, abnormal facial features, and mental retardation. In addition, about 80% of children with FAS have an abnormally small cranium, called microcephaly. Children with FAS also have serious lifelong disabilities, including learning disabilities and behavioral problems.2 3 4 ARND and ARBD are milder versions of FAS.5
Drinking just one alcoholic beverage per day while pregnant has been associated with increased risk of having a child with impaired growth. The potential for harm increases as larger amounts of alcohol are consumed. Even minimal alcohol consumption during pregnancy can increase the risk of hyperactivity, attention deficiency, and emotional problems in the child.6 No safe level of alcohol intake during pregnancy has been determined.7 8
There are many medications that a woman should not use during pregnancy. A healthcare practitioner should review all over-the-counter and prescription medications, as well as any nutritional or herbal supplements. For example, the commonly prescribed acne medication, isotretinoin (Accutane®), a synthetic form of vitamin A, can cause severe birth defects if used during pregnancy.
Excessive noise may have damaging effects on a developing fetus. Many pregnant women are exposed to noise in the workplace.9 10 In one study, the children of women exposed consistently to high levels of occupational noise during pregnancy were more likely to have high-frequency hearing loss (identified at four to ten years of age) than were children whose mothers were not exposed to such noise.11 Noise exposure at these excessive levels (i.e., 85 to 90 decibels) occurs in many occupations, even among women wearing protective hearing devices. Other environmental sources of excessive noise include rock concerts, boom boxes, car stereos, and airport jet traffic.
Women who are obese prior to pregnancy are at increased risk of having an NTD-affected pregnancy. One study showed a twofold or greater risk of NTD-affected pregnancy among women who were obese.12
Nutritional supplements that may be helpful for birth defects prevention
Several studies and clinical trials have shown that 50% or more of NTDs can be prevented if women consume a folic acid-containing supplement before and during the early weeks of pregnancy.13 14 The United States Department of Public Health, the Centers for Disease Control and Prevention (CDC), and the March of Dimes recommend that all women who are capable of becoming pregnant supplement with 400 mcg folic acid daily. Daily supplementation prior to pregnancy is necessary because most pregnancies in the United States are unplanned15 and the protective effect of folic acid occurs in the first four weeks of fetal development,16 before most women know they are pregnant.
For women who have had a previous NTD-affected pregnancy, the CDC recommends daily supplementation with 4,000 mcg per day of folic acid. In a preliminary study, this amount of supplemental folic acid before and during early pregnancy resulted in a 71% reduction in the recurrence rate of NTDs.17
In a preliminary study, women with the highest total dietary zinc intake before pregnancy (including zinc from both food and supplements) had a 35% decreased risk of having an NTD-affected pregnancy.18 However, another preliminary study found no association between blood levels of zinc in pregnant women and the incidence of NTDs.19 Zinc supplementation (15 mg per day) is considered safe for pregnant women. Given its safety and potential role in preventing NTDs, a zinc-containing multivitamin is recommended by many doctors to all women of childbearing age who may become pregnant.
Use of a multivitamin supplement during the periconceptional period (defined as from the three months prior to pregnancy to the third month of pregnancy) can contribute significantly to a healthy pregnancy. Use of a multivitamin during these crucial months of fetal development has been associated with a reduced occurrence of many birth defects. In a preliminary study, periconceptional use of a multivitamin was associated with a lowered risk of heart defects in the offspring.20 This association was not evident when use of the multivitamin began after the first month of pregnancy. The authors of this study concluded that approximately one in four major heart defects could be prevented by periconceptional multivitamin use. In another preliminary study, periconceptional use of a multivitamin was associated with a 43% reduction in the risk of having an infant with a severe heart defect.21
In a double-blind trial, women given a multivitamin containing folic acid starting at least one month before becoming pregnant to at least the second month of pregnancy were much less likely to have a child with a birth defect than were women given a trace mineral supplement.22 The greatest reduction in risk was seen in the occurrence of urinary tract defects and heart defects. A preliminary study found that periconceptional use of a multivitamin reduced the risk for urinary tract defects and limb defects.23 When multivitamin use was begun after the periconceptional period, there was a reduction in risk noted for cleft palate and again for urinary tract defects.
Childhood brain tumor rates may also be reduced by a mother’s intake of a multivitamin while pregnant. In a preliminary study, use of a multivitamin by women for at least two-thirds of their pregnancy was associated with a decreased risk of brain tumor in the offspring compared to women who took a multivitamin for less than two-thirds of the pregnancy.24 The greatest reduction of brain tumor risk (about 50%) was among children whose mothers took a multivitamin throughout the entire pregnancy.
A preliminary study, published in 1995 in the New England Journal of Medicine (NEJM),25 concluded that supplementation with more than 10,000 IU (3,000 mcg) per day of vitamin A can increase the risk of certain birth defects. Since the publication of that report, women who are or could become pregnant have been told by doctors to consume no more than 10,000 IU per day of supplemental vitamin A. However, another study has challenged the findings of the NEJM report. In the new study, pregnancy outcome was determined in several hundred women who had consumed 10,000 to 300,000 IU (averaging about 50,000 IU) of supplemental vitamin A per day during early pregnancy.26 No birth defects occurred in any of the infants exposed to maternal intakes of vitamin A greater than 50,000 IU per day. In fact, when compared with infants not exposed to vitamin A, a 50% decreased risk for birth defects was found in this high-exposure group.
A closer look at the recent study reveals a 32% higher-than-expected risk of birth defects in infants exposed to 10,000 to 40,000 IU of vitamin A per day but, paradoxically, a 37% decreased risk for those exposed to even higher levels. This suggests that both “higher” and “lower” risks may have been due to chance. At present, the level at which birth defects might be caused by vitamin A supplementation is not known, though it may well be higher than 10,000 IU per day. Nevertheless, women who are pregnant should talk with a doctor before supplementing with more than 10,000 IU per day.
Are there any side effects or interactions with birth defects prevention?
Refer to the individual supplement for information about any side effects or interactions.