Oct. 3, 2000 -- Researchers in South Carolina have shown that encouraging women to take folic acid before and during pregnancy reduces their risk of having a baby with birth defects called neural tube defects. Experts recommend that all women of child-bearing age get enough folic acid and that women who want to become pregnant have their folic acid levels tested by a physician.
Neural tube defects occur when part of the maturing nervous system of the developing child, from which both the brain and spinal cord develop, fails to close completely during the first month of pregnancy. Muscle and bone cannot grow across such a gap, causing some of the most serious birth defects, including conditions known as spina bifida, anencephaly, and encephalocele.
In the U.S., about 2,500 babies are born each year with neural tube defects, which is about six in every 10,000 live births. Most often, unborn children affected by neural tube defects do not even survive to birth, and those who do are usually extremely disabled. Although neural tube defects can have a genetic cause, it is known that women who take enough folic acid, or vitamin B-12, especially before pregnancy and during the first month of pregnancy, are far less likely to have a child affected by one of these devastating conditions.
Lead author of the study, Roger E. Stevenson, MD, tells WebMD that his is the first U.S. study of its size to show that if women take folic acid, they are less likely to have children who are affected by neural tube defects. It confirms the role of folic acid in healthy pregnancies that has been demonstrated in studies in other countries. Stevenson is director of the Greenwood Genetic Center in Greenwood, S.C. The study appears in the October issue of the journal Pediatrics.
Stevenson and his team monitored the number of pregnancies that occurred in South Carolina from 1992 to 1998 and identified those affected by a neural tube defect. During this same time, public awareness campaigns were used to inform women of reproductive age about the importance of folic acid, and women who had had children affected by a neural tube defect in the past were advised to take folic acid during any following pregnancy.
Over the six-year monitoring period, the researchers found that the number of women taking folic acid around the time of conception and during pregnancy increased dramatically. Similarly, the number of pregnancies affected by neural tube defects decreased significantly.
The March of Dimes recommends that a woman capable of becoming pregnant consume 400 micrograms of folic acid from foods or supplements daily.
According to expert Satty Gill Keswani, MD, folic acid can be found in some foods, such as green leafy vegetables, but most Americans eat too much frozen and processed foods to get enough of it from diet alone. She recommends that everyone eat more unprocessed vegetables, but that women who are or planning to become pregnant need the extra boost folic acid supplements provide. These women should see their doctor, who can perform blood tests that will tell just how much folic acid, as well as other vitamins and minerals, they need to take. Keswani is a reproductive endocrinologist at St. Barnabas Medical Center in Livingston, N.J., and director of the Livingston Fertility Center.
"Folic acid appears to be an important vitamin that can prevent a certain proportion of birth defects," says expert Alasdair G. W. Hunter, who studies pediatrics and practices as a medical geneticist. Although the major impact is on the neural tube defects, he adds, "it may decrease the rates of certain other malformations." He also says folic acid may play an important role in other aspects of health, such as heart disease, although this remains to be confirmed in studies. Hunter is medical director of the Eastern Ontario Genetics Program at the Children's Hospital of Eastern Ontario.