National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Anencephaly

Back to List of Questions
If anencephaly occurred in a previous pregnancy, what are the chances of this condition affecting the next pregnancy if we take the recommended medication?  How long should the medication be taken before attempting another pregnancy?

The following information may help to address your question:


If anencephaly occurred in a previous pregnancy, what is the chance of this condition affecting the next pregnancy if we take the recommended medication?

Anencephaly is a type of neural tube defect (NTD).  If an NTD occurred in a previous pregnancy, there is up to a 4% chance of each future pregnancy also being affected with an NTD.[1]  However, taking the vitamin folic acid has been proven to reduce the chance of an NTD in future pregnancies.[1]  In one large research study, women who had a previous pregnancy affected by an NTD and who took folic acid prior to and during later pregnancies had an approximately 1% chance of having another pregnancy affected with an NTD.[2]
Last updated: 2/10/2012

If anencephaly occurred in a previous pregnancy, how long should folic acid be taken before attempting another pregnancy?

The Centers for Disease Control and Prevention (CDC) recommends that every woman take 400 micrograms of folic acid daily for at least one month prior to becoming pregnant, and every day during the pregnancy as well, to reduce the chance of neural tube defects.[3]  In families with a history of anencephaly (a type of neural tube defect) in a previous pregnancy, it is recommended that the dose of folic acid be ten times higher, or 4 milligrams per day, beginning at least three months prior to becoming pregnant again and continuing every day during the pregnancy.[1]
Last updated: 2/10/2012

We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please contact us.

Warm regards,
GARD Information Specialist

Please see our Disclaimer.

  1. Best RG. Anencephaly. eMedicine. December 2011; http://emedicine.medscape.com/article/1181570-overview#aw2aab6b5. Accessed 2/8/2012.
  2. Medical Research Council Vitamin Study Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet. 1991; 338:131-137. http://www.ncbi.nlm.nih.gov/pubmed/1677062. Accessed 2/8/2012.
  3. Centers for Disease Control and Prevention. Facts About Folic Acid. Folic Acid Homepage. January 2012; http://www.cdc.gov/ncbddd/folicacid/about.html. Accessed 2/8/2012.