Spina bifida: anticonvulsants and other maternal influences

At least two maternal conditions have been shown to be associated with an increased risk for the occurrence of anencephaly, spina bifida and encephalocele: insulin-dependent diabetes mellitus in the mother and maternal epilepsy for which anticonvulsant treatment is being used. Of 147 infants born at the Brigham and Women's Hospital with anencephaly, spina bifida and encephalocele among 123,489 live-born, still-born and elective terminations surveyed, 7.5% were infants of insulin-dependent diabetics and 0.7% had been exposed to anticonvulsants in utero. In addition to these proven causal associations neural tube defects have been postulated by some, but not all, studies as being more common among infants exposed to hyperthermia in utero and to drugs used to induce ovulation.