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Folic acid supplementation in pregnancy

Lauri Hochberg, MD
Joanne Stone, MD
Section Editor
Louise Wilkins-Haug, MD, PhD
Deputy Editor
Vanessa A Barss, MD, FACOG


Folic acid supplementation and dietary fortification decrease the occurrence and recurrence of neural tube defects (NTDs) and are recommended for women planning pregnancy or capable of becoming pregnant [1-6]. However, it is estimated that only 15 to 25 percent of folic acid-preventable spina bifida and anencephaly worldwide is being prevented through folic acid supplementation and food fortification programs [7].

Folic acid supplementation, usually as part of a multivitamin, has also been associated with a variety of benefits unrelated to NTDs.

This topic will discuss the role of folic acid supplementation for prevention of NTDs, and possibly other congenital malformations. Prenatal screening and diagnosis of NTDs is reviewed separately. (See "Prenatal screening and diagnosis of neural tube defects".)


Although the terms are used interchangeably, folate is a water-soluble B vitamin (B9) that occurs naturally in foods such as beef liver, leafy green vegetables, oranges, and legumes, whereas folic acid is the synthetic form of folate that is found in supplements and added to fortified foods (table 1). The bioavailability of folic acid from supplements and folic acid fortified foods appears to be substantially higher than folate bioavailability from consumption of natural foods [8]. Bioavailability is affected by several factors, including whether the food is raw or cooked, how it is cooked, the combination of foods consumed, and host factors.

Varying degrees of folate deficiency may result from low carbohydrate diets, since bread and pasta are made of fortified grain; some medications (eg, phenytoin, sulfasalazine); high consumption of foods designated as "organic," which are exempt from folic acid fortification regulations; and medical or surgical conditions associated with malabsorption (eg, celiac disease, Crohn's disease, intestinal resection or bypass).


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Literature review current through: Jan 2017. | This topic last updated: Tue Feb 21 00:00:00 GMT+00:00 2017.
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