The Importance of Supplementation Before & During Pregnancy

Creating the optimal environment for a developing fetus is a critical part of pregnancy planning for all those considering becoming pregnant. For patients with epilepsy, a healthy supplementation routine can help reduce certain risks and promote healthy pregnancy outcomes.

Folic acid supplementation is recommended in all people with epilepsy with childbearing potential, regardless of immediate plans for pregnancy. Ideally, patients should start taking prenatal supplements before trying to get pregnant, so discuss the benefits of supplementation with patients of childbearing years as soon as possible. It is important that the person begins supplementing with folic acid well before pregnancy and continues it throughout pregnancy, while breastfeeding, and between babies.

Topics covered on this page include:

The Value of Folic Acid During Childbearing Years

Patients should take folic acid daily. Because some studies found that up to 65% of women with epilepsy reported at least one unplanned pregnancy, clinicians should start patients on folic acid as soon as the patient enters their childbearing years.  

The benefits of folic acid supplementation prior to and continuing through pregnancy are well-documented. It is associated with:

  • Lower risk of neural tube defects in the general population.
  • Improved neurodevelopmental outcomes, including a decreased risk of autism spectrum disorder, in both patients with epilepsy and the general population.

Recommendations for Folic Acid Dosage

We recommend that patients with epilepsy and childbearing potential should take at least 400-1000 mcg of folic acid daily. In the United States, 1000 mcg (1 mg) can be prescribed as a tablet. This supplementation should continue throughout their childbearing years, including pregnancy, breastfeeding, and between babies. Patients seeking pregnancy should add prenatal vitamins to the folic acid. Most prenatal vitamins have around 800 mcg of folic acid. A common practice is to prescribe 1000 mcg (1 mg) of folic acid and add a prenatal vitamin (1800 mcg or 1.8 mg total dose). If the patient isn’t on either folic acid or prenatal vitamins prior to pregnancy, both should be started immediately upon detection of pregnancy.

NOTE:  Historically, “high dose” folic acid (> 4000 mcg) was recommended to all patients with epilepsy. There is little evidence, however, that this has benefit for most pregnant patients and there may be some associated risks. High dose folic acid may reduce the risk of neural tube defects in the setting of a personal or family history of neural tube defects. In patients of childbearing potential taking valproic acid, primidone, or carbamazepine, some clinicians consider higher doses of folic acid.

Other Vitamin Supplements

Folic acid isn’t the only supplement recommended during pregnancy. We recommend:

  • Prenatal vitamins ideally three months prior to trying for pregnancy (this will add 800-1000 mcg of folic acid).
  • Checking a patent's B12 level to ensure folic acid is not masking a B12 deficiency and supplement accordingly.
  • Measuring vitamin D levels ahead of (or even during) pregnancy and supplement accordingly.

Guide Your Patients

Folic acid supplementation (and later prenatal vitamins and other supplements) is a critical step to creating the best possible environment for a developing fetus and a healthy baby. Due to the high chance of unplanned pregnancy, folic acid should be prescribed and emphasized even before pregnancy planning.

Folic acid (and prenatal vitamins) should be addressed as part of pregnancy planning discussions that include other planning steps like switching to a lower-risk ASM that set the patient up for better outcomes. 

Reviewed by: EPMC Expert Panel, March 2025