The use of drugs in mothers of offspring with neural-tube defects.

OBJECTIVE: To study the risk of maternal drugs use during pregnancy in the origin of isolated neural-tube defects (NTD).
MATERIALS AND METHODS: 1202 cases with NTD, 38,151 population controls without any defects and 22,475 patient controls with other defects were compared in the population-based data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities (HCCSCA), 1980-1996. The HCCSCA contains 542 drugs, however only those drugs were evaluated which included five or more mothers in the NTD group. Drugs with the same chemical structures were combined. In addition, only drug use in the second month of pregnancy was evaluated because it is the critical period for NTD. Of course, it is necessary to exclude different biases, mainly recall bias at the evaluation of these drugs. Of 121 chemicals, only oxytetracycline, carbamazepine and valproic acid had some association with NTD. High doses of exogenous oestrogens, clomiphene, chorionic gonadotropin, lynesterol and ergotamine also seemed to have some indirect association with NTD because their exposures occurred more frequently before the critical period of NTD due to maternal infertility.
CONCLUSION: Our findings suggest that drugs used during pregnancy do not appear to substantially contribute to the occurrence of isolated NTD but some drugs have a role in the origin of these defects.