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How many people are affected by or are at risk for neural tube defects?

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In the United States, about 1,500 infants are born each year with spina bifida.1

The other types of neural tube defects are less common. About 340 infants are born in the United States each year with an encephalocele, and about 860 are born with anencephaly.1 Iniencephaly is estimated to occur in 0.1 to 10 per 10,000 births.2 Anencephaly and iniencephaly are more common in females. Many pregnancies that involve anencephaly end in miscarriage.

These conditions are more common in infants born to Hispanic women than those born to non-Hispanic white and non-Hispanic black women.

Parents who have already had a child with spina bifida or another neural tube defect have a 4% risk of having a second child with spina bifida. Parents who already have two children with spina bifida have about a 10% chance of having another child with this condition. When one parent has spina bifida, there is about a 4% chance that his or her child also will have it.3 Women who have had one pregnancy with anencephaly have a 2% to 3% risk of having a second neural tube defect in later pregnancies.4To help prevent recurrence, health care providers recommend that these women take 4 mg of folic acid supplements a day starting 3 months before conception. This dosage is 10 times the 400 mcg normally recommended.


  1. Centers for Disease Control and Prevention. (2011). Spina bifida: Data and statistics. Retrieved May 19, 2012, from http://www.cdc.gov/ncbddd/spinabifida/data.html [top]
  2. Pungavkar, S. A., Sainani, N. I., Karnik, A. S., Mohanty, P. H., Lawande, M. A., Patkar, D. P., et al. (2007). Antenatal diagnosis of iniencephaly: Sonographic and MR correlation: A case report. Korean Journal of Radiology, 8, 351–354. [top]
  3. Chescheir N., & American College of Obstetricians and Gynecologists (ACOG) Committee on Practice Bulletins-Obstetrics. (2003). ACOG Practice Bulletin: Neural tube defects, Number 44. International Journal of Gynecology and Obstetrics, 83, 123–133. [top]
  4. Children’s Hospital of Wisconsin. (2012). Anencephaly. Retrieved June 20, 2012, from http://www.chw.org/display/PPF/DocID/34371/Nav/1/router.asp External Web Site Policy [top]

Last Updated Date: 11/30/2012
Last Reviewed Date: 11/30/2012
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