Neural tube defects: epidemiology, detection, and prevention.

Neural tube defects are common congenital malformations of the central nervous system and include anencephaly, spina bifida, and encephalocele. Prenatal detection by amniotic fluid analysis of alpha-fetoprotein is possible in those women known to be at high risk for neural tube defects. Maternal serum screening for increased alpha-fetoprotein levels is now available nationally and has the potential to identify women who otherwise would not be known to be at risk. The epidemiology, detection, screening, and prevention of neural tube defects are discussed, and an explanation of alpha-fetoprotein and its use in screening is offered.