Clomiphene and neural tube defects.

THE aetiology of anencephaly and/or spina bifida (neural tube defects) is still obscure. Most investigators are now agreed on a multifactorial causation with an important genetic factor and a substantial environmental component. The genetic factor is probably polygenic, but the mechanism by which it acts remains unknown. Recently, drugs that stimulate ovulation, particularly clomiphene, have been implicated in the aetiology of neural tube defects (Dyson & Kohler, 1973; Sandler, 1973; Barrett & Hakim, 1973; Field & Kerr, 1974). Although six infants with anencephaly and/or spina bifida have been born to mothers receiving clomiphene, it is impossible on present evidence to conclude whether the malformation rate for neural tube defects is greater than would have been expected. This report describes four patients on clomiphene who produced a total of five infants each with a neural tube defect.