Rates of anencephaly and spina bifida anmong sibs of probands affected by anencephaly or spina bifida

Smithells et all have offered data on an experiment in periconceptional vitamin supplementation in women known to be at high risk of producing an infant with neural tube defects. The women were ascertained by having already produced such an infant. Logically the best design for such an experiment would be to form matched pairs of such women and to give… CONTINUE READING