Population-based case-control study of mebendazole in pregnant women for birth outcomes.

The objectives of the study was to check the embryotoxic-teratogenic and fetotoxic effect of mebendazole (Vermox; Richter, Budapest, Hungary) treatment during pregnancy. Mebendazole use during pregnancy was evaluated in mothers of babies born with congenital abnormalities and in matched control mothers of babies born without congenital abnormalities in the population-based data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities between 1980 and 1996. Of 22,843 women who had newborns or fetuses with congenital abnormalities, 14 were found to have been treated with mebendazole for intestinal nematoda infections/diseases during pregnancy (crude POR: 1.8 with 95% CI: 0.7-4.2). Of 38,151 women who had newborns without any defects (controls), the same number (14) were found to have been treated with mebendazole during pregnancy. Six different congenital abnormality groups were evaluated and a higher prevalence of mebendazole use in these mothers throughout pregnancy was not found. Gestational age and birth weight were analyzed in control infants born to mothers with or without mebendazole treatment. The mean gestational age was somewhat longer and mean birth weight was larger in newborn infants born to mothers with mebendazole treatment. Thus, treatment with mebendazole during pregnancy did not indicate a teratogenic and fetotoxic risk to the embryo or fetus, though the numbers of treated cases and controls in this study were limited.