A population-based case-control teratologic study of nalidixic acid.

OBJECTIVE: Quinolones, mainly nalidixic acid, are frequently used in Hungary to treat bacterial infections in pregnant women, but so far no controlled epidemiological studies of congenital abnormalities among infants born to women treated with nalidixic acid during pregnancy have been reported. METHODS: The analysis of oral nalidixic acid use during pregnancy in the mothers of cases with congenital abnormalities and in their matched population controls without congenital abnormality was carried out in the population-based dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities between 1980 and 1996. The study included 22865 women who had newborns or fetuses with congenital abnormalities, and 38151 pregnant women who had newborn infants without any defects (controls). RESULTS: In the case group, 242 (1.1%) and in the control group, 377 (1.0%) pregnant women were treated with nalidixic acid (crude OR: 1.1 with 95% CI: 0.9-1.3). Seventeen different congenital abnormality groups were evaluated and a higher prevalence of pyloric stenosis was found in seven case infants born to mothers who received nalidixic acid treatment during the last months of pregnancy (adjusted OR: 11.0 with 95% CI: 1.3-91.4). CONCLUSIONS: Treatment with nalidixic acid during pregnancy may increase the risk of pyloric stenosis, though the chance effects cannot be excluded.