One of the main questions women ask when they are considering pregnancy is if there is anything they can do to prevent birth defects. Folic acid is recommended for all women of childbearing age who are contemplating pregnancy. Folic acid has been shown to prevent neural tube defects in first time mothers as well as prevent neural tube defects in mothers who have had a prior baby with a neural tube defect. Neural tube defects can affect the spine (spina bifida), the brain (anencephaly) or the skull (acrania). Spina bifida is a condition in which a portion of the spinal cord and the surrounding structures develops outside the body. Anencephaly is a condition in which the brain and skull bones do not form properly and results in parts of the brain being missing.
Folate is a water-soluble B vitamin, which is found in foods like beef liver, leafy green vegetables, oranges and legumes. Folic acid is the synthetic form found in vitamin supplements. Folate deficiency can occur in low carbohydrate diets, because of certain medications (like certain anti-seizure medications or antibiotics), high consumption of “organic” foods (which are exempt from folic acid fortification regulations) and certain medical or surgical conditions (like celiac disease or gastric bypass).
Folic acid supplementation should begin one month prior to pregnancy and continue for at least the first trimester, or the first 12 to 14 weeks of pregnancy. The recommended dose is at least 4 micrograms of folic acid per day. This is because the neural tube closes in the first 4 to 7 weeks of embryonic life which is before many women know they are pregnant and before they have seen an obstetric provider. It is for this reason that all women of childbearing potential should be on folic acid supplementation. Patients who have multiples (ie, twins, triplets) should also be taking at least 1 mg of folic acid per day in their first trimester.
Women with a prior child with a neural tube defect and women taking anti-seizure medications (i.e., valproic acid and carbamazepine) are at the highest risk of having an affected child. Higher doses of folic acid at a dose of 4 to 5 mg are recommended in these women. Women should not attempt to take 4 mg of folic acid by taking multiple multivitamins as the can ingest harmful levels of other vitamins like vitamin A. One prenatal vitamin per day and 1 mg of folic acid three times a day is a practical way to get the full dose needed in high risk women. Most pills containing 1 mg or more of folic acid require a prescription in the United States. Prescription prenatal vitamins typically contain 1 mg of folic acid. Some experts also recommend higher doses of folic acid supplementation in women with insulin dependent diabetes, obesity, a family history of neural tube defects in a second or third degree relative and women with certain genetic predispositions to abnormal folate metabolism (ie, MTHFR gene mutation).
Most women (95 percent) who deliver infants with neural defects have no history of a prior affected child and are not on anti-seizure medications. There have been multiple national organizations conducting educational campaigns to inform women about the need for additional folate intake. Still, only 40 percent of women report daily consumption of a vitamin containing folic acid, 60 to 80 percent of women know that it can reduce birth defects and only 10 percent of women know that it must be taken before conception. To prevent folate deficiency and its consequences, in 1988 the U.S. Food and Drug Administration decided to fortify the food supply with folic acid supplementation, mandating that enriched grain products be fortified in order to ensure that women receive a minimum daily intake of 400 micrograms of folic acid. Some oral contraceptive pills also contain folic acid.
Adequate intake of folic acid will not prevent all cases of neural tube defects. There are situations in which they may still occur, such as women with diabetes who have poor glucose control in the first trimester, exposure to hyperthermia and certain chromosome abnormalities or genetic syndromes in the fetus. There is some data suggesting that folic acid prevents other birth defects, miscarriage, preterm birth or perinatal death but these potential benefits require further study and confirmation. It is always important to talk with your health care provider about any other thing you can do to prevent complications in your pregnancy.