Population-based case control study of the safety of sulfasalazine use during pregnancy

Background: We studied the human teratogenic risk of sulfasalazine because this drug interferes with folate metabolism. Methods: Case control study within the Hungarian Case Control Surveillance of Congenital Abnormalities, 1980-1996; based on 22 865 new-born infants or foetuses with congenital abnormalities, and 38 151 babies without any detected congenital abnormalities (control group). Results: Seventeen pregnant women (0.07%) were treated with sulfasalazine in the case group, and 26 (0.07%) in the control group. The overall adjusted adds ratio of congenital abnormalities after sulfasalazine treatment was odds ratio = 1.2 (95% confidence interval: 0.6-2.1). None of the analyses indicated any significant increased prevalence of selected congenital abnormalities among the exposed compared with the not exposed. Conclusions: We found no significant increased prevalence of selected congenital abnormalities in the children of women treated with sulfasalazine during pregnancy. However, the amount of information is limited and additional data are needed to rule out a teratogenic effect.