Discoveries and Data: Specific Conditions



Found in about 1 in 1,480 pregnancies in California, neural tube defects—a group of conditions affecting the brain and spinal cord—are common, serious birth defects with substantial public health impact.


The neural tube develops about 18-30 days after conception, often before a woman realizes she is pregnant. (This is about the time of the first missed menstrual period.) As the embryo develops, 2 growing tissue ridges fold up and fuse, forming a cylinder. This is the neural tube, the precursor of the brain and spinal cord. Unless the cylinder is fully closed, nerve tissue and bones will not develop normally and a neural tube defect results.

The most common neural tube defects are spina bifida, an opening in the spinal cord and backbone, and anencephaly, absence of most of the brain and skull. About 20% of infants with neural tube defects have other major birth defects as well.

All babies with anencephaly die. For those with spina bifida, the average lifetime cost for medical treatment, educational services and lost productivity is $294,000.

Expanded AFP screening, a prenatal blood test, can identify 80% of pregnancies with spina bifida and 97% with anencephaly. Prenatal diagnosis is also possible with ultrasound and/or amniocentesis.


bullet-8129146 Neural tube defects are more common in Latino infants, particularly if mothers are born outside the US.
bullet-8129146 The rate in Mexico is more than 5 times higher than in US Whites. Mexican-born mothers giving birth in the US have half the risk of their counterparts in Mexico, but more than twice the risk of second-generation Mexican-Americans.
bullet-8129146 This difference is not necessarily explained by known risk/protective factors such as socioeconomic status or vitamin use nor by differential use of prenatal diagnosis.

  arrow_right-4293143 More on neural tube defects