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Folic acid supplementation in pregnancy

Laura M Goetzl, MD, MPH
Section Editor
Louise Wilkins-Haug, MD, PhD
Deputy Editor
Vanessa A Barss, MD, FACOG


Periconceptional folic acid supplementation decreases the occurrence and recurrence of neural tube defects (NTDs). It is recommended for all women planning pregnancy or capable of becoming pregnant. Preconception patient education about the need for prophylaxis is important during medical wellness visits as many women are not aware of this recommendation until after they seek prenatal care or choose not to follow the recommendation because of cost or inconvenience [1,2]. Women who do not take supplements still consume some folic acid as folate is a natural component of a variety of foods, and grain products in many countries are fortified with folic acid.

This topic will discuss the role of folic acid supplementation for prevention of NTDs, dosing in women at average versus high risk of NTDs, potential benefits unrelated to NTDs, potential risks of supplementation, and NTDs that occur despite supplementation. Prenatal screening and diagnosis of NTDs are reviewed separately. (See "Open neural tube defects: Risk factors, prenatal screening and diagnosis, and pregnancy management".)


Although the terms folate and folic acid are often used interchangeably, folate is a water-soluble B vitamin (B9) that occurs naturally in foods, and folic acid is the synthetic form of folate.

Sources — Folate (B9) occurs naturally in several foods, including beef liver, leafy vegetables, peas and beans, avocados, eggs, and milk [3,4].

Folic acid is available in multivitamins, prenatal vitamins, and as a pure folic acid supplement. It is also added to fortify certain foods, including flour, pasta, breads, cereals, cornmeal, and rice, and it has been added to some oral estrogen-progestin contraceptive pills to ensure adequate baseline folate levels in the event of unplanned pregnancy from inconsistent/incorrect contraceptive use or conception soon after discontinuation.

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Literature review current through: Nov 2017. | This topic last updated: Dec 12, 2017.
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