Health Professionals:

Folic Acid and NTDs

There is substantial evidence that periconceptional (before conception and during early pregnancy) use of folic acid reduces the incidence of neural tube defects (NTDs).  It is estimated that up to 70 percent of NTDs could be prevented if all women who can become pregnant consume 400 micrograms of folic acid from at least a month before conception through the first trimester of pregnancy.

Recommendation History

Based on substantial scientific evidence, in September 1992, the U.S. Public Health Service recommended that:

• All women of childbearing age in the United States who are capable of becoming pregnant consume 400 micrograms of folic acid per day for the purpose of reducing their risk of having a pregnancy affected with spina bifida or other NTDs.
• Women who have had a previous NTD-affected pregnancy consume 400 micrograms of folic acid daily, unless they are planning a pregnancy, in which case they should consult their physician about consuming 4 milligrams (4,000 micrograms) of folic acid every day for NTD recurrence prevention.

In 1998 the Institute of Medicine (now known as the National Academy of Medicine) issued the following recommendation as part of the Dietary Reference Intakes for folate:

• Women capable of becoming pregnant consume 400 micrograms of folate daily from supplements, fortified foods, or both in addition to consuming food folate from a varied diet.

To assist women in getting adequate levels of folic acid for NTD risk reduction, the Food and Drug Administration issued a regulation in 1996 requiring that by January 1998 all enriched cereal grain products be fortified with folic acid to reduce the risk of neural tube defects in newborns. Fortification (140 micrograms folic acid per 100 grams cereal grain product) began in 1996 and the process was essentially complete by mid-1997.

Consensus About Prevention

Different organizations, as well as federal and state agencies--including the Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA), the National Academy of Medicine (formerly known as the Institute of Medicine), the American College of Medical Genetics, the Teratology Society, and the American Academy of Pediatrics--have issued statements regarding folic acid supplementation and fortification. They have all followed essentially the same recommendations of the Public Health Service.

The general consensus today can be summarized as follows:

Prevention of first occurrence

• All women of childbearing age who are capable of becoming pregnant are recommended to consume 400 micrograms of synthetic folic acid daily and to eat a healthy diet that includes folate-rich foods.
• Since neural tube closure occurs between 22 and 28 days after conception, which is before the recognition of pregnancy by most women, and because approximately 45% of pregnancies are unplanned, NTD prevention will be best achieved by adequate folic acid intake by all women of childbearing age who are sexually active and capable of becoming pregnant.
• Although not all occurrences of NTDs can be prevented with folic acid, the CDC estimates a 50-70% reduction in NTDs if recommendations for adequate folic acid intake for women are followed.

Prevention of recurrences

• Women with a previous pregnancy resulting in a fetus with an NTD are advised to take a separate supplement of 4 milligrams (4,000 micrograms) of folic acid daily, at least 4 weeks before conception and throughout the first 12 weeks of pregnancy.
• Women should be advised not to attempt to achieve these doses of folic acid by taking over-the-counter or prescription multivitamins with folic acid because of the possibility of ingesting harmful levels of vitamins and minerals.
• It should be noted that 4 milligrams (4,000 micrograms) of folic acid did not prevent all recurrences of NTDs in an intervention study. Therefore, high-risk patients should be cautioned that folic acid supplementation does not preclude the need for counseling or consideration of prenatal testing for NTDs.