The Outcome of Pregnancies before and after the Birth of Infants with Nervous System Malformations

Abstract
SUMMARY: Amongst 1,683 viable infants born prior to the birth of 719 propositi with neural tube defects, the incidence of similar defects was 4–2 per cent. Amongst 313 viable infants born subsequent to the birth of 220 propositi with anencephaly and spina bifida, 5.1 per cent had neural tube defects. There is a tendency for particular neural tube defects to ‘breed true’ within sibships, and this is most marked when more than two sibs are affected.