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QuickStats: Spina Bifida and Anencephaly Rates* --- United States, 1991, 1995, 2000, and 2005

* Per 100,000 live births. Annual data on birth defects are based on information reported on birth certificates provided through the National Vital Statistics System. Because of challenges associated with the reporting of birth defects during the period immediately after birth, spina bifida and anencephaly are considered underreported on birth certificates. Additional information is available at

Excludes data from Maryland, New Mexico, and New York, which did not require reporting for certain years.

§ 95% confidence interval.

Neural tube defects (NTDs) are serious birth defects of the brain (anencephaly) and spine (spina bifida). Since 1992, a national health recommendation has called for women of childbearing age in the United States to consume 400 µg of folic acid daily to reduce their risk for having a pregnancy affected by NTDs. The spina bifida rate per 100,000 live births declined 25% from 1995 to 2000 and 13% from 2000 to 2005. The anencephaly rate declined 36% from 1991 to 1995 and was unchanged from 1995 to 2005.

SOURCE: Mathews TJ. Trends in spina bifida and anencephalus in the United States, 1991--2005. National Vital Statistics System. Available at

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Date last reviewed: 1/10/2008


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