Prevention of Birth Defects

Prevention of Birth Defects
In the past ten years, there have been significant
strides in understanding ways to prevent some birth
defects. For example, a daily supplement to the diet
of 500 micrograms of folic acid, a B vitamin, has been
shown to prevent up to 70 percent of cases of neural
tube defects. Neural tube defects, which include an-
encephaly, spina bifida, and encephalocele, are seri-
ous and often lethal birth defects of the spine and
central nervous system. The recognition that many of
these birth defects can be prevented with folic acid
has led to initiatives at the state and national levels
aimed at educating women about the importance of
consuming the appropriate amount of this vitamin on
a daily basis. In 1996 the U.S. Food and Drug Admin-
istration issued a rule (effective January 1, 1998) re-
quiring that all enriched grain products sold in the
United States be fortified with 140 micrograms of
folic acid per 100 grams of product. As a result of
these public health initiatives, the rate of spina bifida
and anencephaly has declined substantially since the
early 1990s.
Because several birth defects are caused by infec-
tions, prevention initiatives also emphasize immuni-
zation and information. For example, because of
widespread vaccination for rubella (German measles),
the birth defects caused by this infection rarely occur
in the United States. Information about the risk of
birth defects resulting from maternal infection with
syphilis or other sexually transmitted diseases may
stimulate the development of services to help women
at greatest risk. Cytomegalovirus, the most common
of the congenital viral infections, affects almost
40,000 infants each year. It can be passed through
bodily fluids, such as saliva, blood, and breast milk. It
is often passed to a pregnant woman from a child who
is infected but is not showing symptoms; for example,
an infected child may sneeze and then touch a preg-
nant woman, thus infecting her. An infant born to a
mother who has contracted cytomegalovirus is at an
increased risk for mental retardation and vision or
hearing loss.
Although many types of birth defects are prevent-
able, prevention is complicated by the fact that most
serious birth defects occur during the early weeks of
56 BIRTH DEFECTSThe specific cause of many birth defects is unknown, but several factors associated with pregnancy and delivery can increase the risk of
birth defects. Nongenetic factors such as a variety of medications and drugs are known to cause abnormalities in newborns. (Electronic
Illustrators Group)
pregnancy, often before a woman even knows she is
pregnant. This is why strategies aimed at preventing
birth defects must focus on improving the health
of women prior to pregnancy. Screening and diag-
nostic tests, such as ultrasound, maternal serum
a-fetoprotein screening, amniocentesis, and chorion-
ic villus sampling, are used to monitor the health of
the fetus and to identify certain fetal malformations
and chromosomal disorders; they cannot, however,
be used to prevent these conditions from occurring.
Decisions about whether to use prenatal testing,
which tests are appropriate, and how to use the results
must be made by the mother in conjunction with her
physician