Spina bifida is the common name for a range of birth defects caused by problems with the early development of the spine. The term comes from the Latin "spina," meaning thorn, or "spine," and "bifida," meaning split into two parts. The main defect of spina bifida involves an abnormal opening in the bony column through which the spinal cord passes, called the vertebral column. In spina bifida, there is an abnormal opening somewhere along the vertebral column, which leaves the spinal cord unprotected, and vulnerable to either mechanical injury or invasion by infection.

Spina bifida occurs in one out of every 700 births to whites in North America, but in only one in every 3,000 births to African-Americans. In some areas of Great Britain, the occurrence of spina bifida is as high as one in every 200 births. Spina bifida tends to run in families, leading researchers to suspect...