Given recent discussions within our group and with our colleague, Lewis Holmes, MD, chief of the Genetics and Teratology Unit at Massachusetts General Hospital for Children and director of the North American AED (Antiepileptic Drug) Pregnancy Registry, I wanted to expand upon a previous blog post. In the initial post, I wrote that women who take certain medications, like mood stabilizers or antiepileptic drugs, are advised to take increased doses of folic acid before pregnancy and throughout pregnancy.
Specifically, first trimester exposure to the anticonvulsant valproic acid has been associated with an increased risk of neural tube defects, as well as other structural abnormalities. This finding led to the recommendation that women on valproic acid should take an increased daily dose (4 mg) of folic acid. While research has not shown lamotrigine, a commonly prescribed mood stabilizer, to be associated with an increased risk of neural tube defects, the recommendation regarding folic acid supplementation has been broadened to include women taking any anticonvulsant. It is now recommended that women on antiepileptic drugs take 4 or 5 mg of folic acid daily before conception and during early pregnancy.
Research has shown that folic acid supplementation decreases the overall risk of neural tube defects in the general population, yet it has not been demonstrated that folic acid supplementation decreases the risk of neural tube defects or other malformations when given to women taking anticonvulsant drugs. It is hoped that the risk of neural tube defects and other structural defects may be decreased by supplementation with higher doses of folic acid; the 4-5 mg recommended daily dosage of folic acid has not been shown to be harmful to the pregnant woman or her fetus.
In addition to taking an increased daily dose of folic acid, all women who are planning to conceive or who are pregnant, should be taking a daily multivitamin tablet or prenatal vitamin which includes Vitamin B12. Recent studies have shown that multivitamin supplementation has decreased the rates of several different types of congenital malformations, including neural tube defects.
April Hirschberg, MD
Wilson RD et al. Pre-conceptional vitamin/folic acid supplementation 2007: the use of folic acid in combination with a multivitamin supplement for the prevention of neural tube defects and other congenital anomalies. Obstet Gynaecol Can 2007;29(12): 1003-26.
Goh YI et al. Prenatal multivitamin supplementation and rates of congenital anomalies: a meta-analysis. J Obstet Gynaecol Can 2006;28(8): 680-9.