Fetal mortality in sibships of cases with neural tube defects.

Rates of fetal mortality in sibships of probands with neural tube defects (NTDs) may reflect liability to NTDs. Expectations from the multifactorial model predict that fetal loss should be higher in sibships of male probands; in multiplex sibships; and sibships where the proband had no additional malformations. This was analysed for 715 pregnancies from 398 sibships. In general, the results did not support the expectations of the multifactorial model.