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Approximately 120,000 babies born in the United States each
year are affected by birth defects. Birth defects account for more than 20% of infant deaths and contribute
substantially to life-long disabilities. The causes of an estimated 70% of all birth
defects are unknown. Some factors that contribute to birth defects include
various occupational hazards, dietary factors, medications,
personal habits, and environmental exposures,
but many questions remain about the exact nature of their influence.
Neural tube defects (NTDs), one of the most common birth
defects, occur in approximately 4,000 pregnancies in the United States each
year. 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.
Women who are obese prior to pregnancy
have been shown to have an increased risk of an NTD-affected pregnancy
occurring. One study showed the risk to be twofold or even greater of an obese
woman having an NTD-affected pregnancy.
Some dietary changes may be helpful in
the prevention of birth defects. According to one study, drinking beverages containing caffeine
may increase the risk of miscarriage among non-smoking women. 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. 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. These findings indicate that there may be no “safe”
amount of regular caffeine consumption during pregnancy. Caffeine is found in
coffee, tea, caffeinated soda, cocoa, chocolate and some over-the-counter
medications.
Changes in lifestyle and habits can also
be helpful in preventing birth defects. Pregnant women should avoid alcohol
completely as alcohol intake lead to a variety 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. Additionally, 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. ARND
and ARBD are simply milder versions of FAS.
Women who drinking just one alcoholic beverage per day while pregnant
have an increased risk of having a child with impaired growth. Even
minimal alcohol consumption during pregnancy can increase the risk of attention deficiency,
hyperactivity, and emotional problems in the child. The
potential for harming the fetus increases as larger amounts of alcohol are
consumed and no
safe level of alcohol intake during pregnancy has been determined.
Certain medications can also be harmful during
pregnancy, therefore all over-the-counter and prescription
medications, as well as any nutritional or herbal supplements, should be
reviewed by your healthcare provider before use.
Excessive noise may also have damaging effects on a developing fetus.
One study showed that the
children of women exposed consistently to high levels of occupational noise
during pregnancy were more likely to have high-frequency hearing loss than were children whose mothers were
not exposed to similar noise levels. Noise exposure at these excessive levels occurs in many occupations,
and can come from other environmental sources including rock
concerts, car stereos, and airplane traffic.
A number of studies and clinical
trials have shown that 50% or more of NTDs could be prevented if women consume a
folic acid-containing supplement before and during the early weeks of pregnancy. 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 highly recommended because
the majority of
pregnancies in the United States are unplanned and the protective effect of
folic acid occurs in the first four weeks of fetal development, 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.
Preliminary studies on zinc consumption
before and during pregnancy have had differing results, from one study that
showed a 35%
decreased risk of having an NTD-affected pregnancy to another study that found no association between blood levels of zinc in pregnant
women and the incidence of NTDs. Zinc supplementation of 15 mg per day is
considered safe for pregnant women and 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) has been associated with a reduced
occurrence of many birth defects and can
contribute significantly to a healthy pregnancy.
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