A case-control study of congenital abnormality and dimenhydrinate usage during pregnancy.

OBJECTIVE: The objective was to determine the teratogenicity of dimenhydrinate, an anti-emetic drug.

METHODS: We compared patients with congenital abnormalities with matched normal controls. Cases were taken from the population-based data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities between 1980 and 1996, while matched controls were from the National Birth Registry of the Central Statistical Office.

RESULTS: Out of 38,151 newborn infants with no congenital abnormalities (control group), 1,726 (4.5%) were treated with dimenhydrinate during pregnancy, while out of 22,843 cases with congenital abnormalities, the number was 914 (4.0%; unadjusted prevalence odds ratio with 95% confidence interval: 0.9, 0.8-1.0). There was thus no indication of teratogenicity with dimenhydrinate. However, a lower rate of obstructive uropathy was found in infants born to mothers treated with dimenhydrinate during the first trimester of pregnancy than in infants whose mothers did not take the drug at that time.