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 anencephaly, spina bifida, and encephalocele, are serious 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 Administration issued a rule (effective January 1, 1998) requiring 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 infections, prevention initiatives also emphasize immunization 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 pregnant 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 preventable, prevention is complicated by the fact that most serious birth defects occur during the early weeks of The 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 diagnostic tests, such as ultrasound, maternal serum a-fetoprotein screening, amniocentesis, and chorionic 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.