Neural tube defects, spina bifida, anencephalus, and encephalocoele, are among the commonest severe congenital abnormalities in most countries. The last decade has seen many advances, including the use of antenatal diagnosis by chemical and ultrasound methods, population screening, and many
new findings in epidemiology, culminating in the demonstration of the protective effect of folic acid on recurrences. The progress in both antenatal diagnosis...