The Role of Folic Acid
While researchers don't know why folic acid helps prevent birth defects, it has been shown to decrease the risk of the most common NTDs: spina bifida (the leading cause of childhood paralysis) and anencephaly (a fatal condition in which an infant is born with a severely underdeveloped brain and skull).
Not only does folic acid combat these NTDs, but it may also help keep your baby from developing a heart defect, cleft lip, or cleft palate.
Additionally, a pregnant woman needs folic acid to help support the rapid growth of the placenta and fetus. The nutrient aids in baby's DNA production. Cell division and fetal growth can become impaired without it. One study found that women with folic acid deficiencies were two to three times more likely to have a premature baby or a baby of low birth weight than those who got enough of the vitamin.