Diet & Fitness

Several studies and clinical trials have shown that 50% or more of NTDs can be prevented if women consume a folic acid-containing supplement before and during the early weeks of pregnancy.^1,2 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 necessary because most pregnancies in the United States are unplanned³ and the protective effect of folic acid occurs in the first four weeks of fetal development,⁴ 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.⁵

In a preliminary study of California mothers, those who had higher intakes of choline during the three months prior to conception were significantly less likely to give birth to a child with an NTD, compared with women with lower choline intakes.⁶ The possibility that choline may protect against NTDs is plausible, as choline has similar biochemical effects as folic acid, which is known to reduce NTD risk.

In a preliminary study of California mothers, those who had higher intakes of choline during the three months prior to conception were significantly less likely to give birth to a child with an NTD, compared with women with lower choline intakes.⁷ The possibility that choline may protect against NTDs is plausible, as choline has similar biochemical effects as folic acid, which is known to reduce NTD risk.

Use of a multivitamin supplement during the periconceptional period (defined as from the three months prior to pregnancy to the third month of pregnancy) can contribute significantly to a healthy pregnancy. Use of a multivitamin during these crucial months of fetal development has been associated with a reduced occurrence of many birth defects. In a preliminary study, periconceptional use of a multivitamin was associated with a lowered risk of heart defects in the offspring.⁸ This association was not evident when use of the multivitamin began after the first month of pregnancy. The authors of this study concluded that approximately one in four major heart defects could be prevented by periconceptional multivitamin use. In another preliminary study, periconceptional use of a multivitamin was associated with a 43% reduction in the risk of having an infant with a severe heart defect.⁹

In a double-blind trial, women given a multivitamin containing folic acid starting at least one month before becoming pregnant to at least the second month of pregnancy were much less likely to have a child with a birth defect than were women given a trace mineral supplement.¹⁰ The greatest reduction in risk was seen in the occurrence of urinary tract defects and heart defects. A preliminary study found that periconceptional use of a multivitamin reduced the risk for urinary tract defects and limb defects.¹¹ When multivitamin use was begun after the periconceptional period, there was a reduction in risk noted for cleft palate and again for urinary tract defects.

Childhood brain tumor rates may also be reduced by a mother’s intake of a multivitamin while pregnant. In a preliminary study, use of a multivitamin by women for at least two-thirds of their pregnancy was associated with a decreased risk of brain tumor in the offspring compared to women who took a multivitamin for less than two-thirds of the pregnancy.¹² The greatest reduction of brain tumor risk (about 50%) was among children whose mothers took a multivitamin throughout the entire pregnancy.

In a preliminary study, women with the highest total dietary zinc intake before pregnancy (including zinc from both food and supplements) had a 35% decreased risk of having an NTD-affected pregnancy.¹³ However, another preliminary study found no association between blood levels of zinc in pregnant women and the incidence of NTDs.¹⁴ Zinc supplementation (15 mg per day) is considered safe for pregnant women. 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.