The teratogenic potential of oral and topical corticosteroid treatment during pregnancy was evaluated in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1994. Corticosteroid tablet pregnancy exposure was 1.55% among 20,830 malformed cases and 1.41% among 35,727 healthy control births (P = 0.2). Corticosteroid ointment pregnancy exposure was 0.35% among malformed and 0.33% among control births (P = 0.7). The absolute risk of oral and ointment corticosteroid treatment was low in pregnancy and particularly in the second and third months of gestation, i.e., in the critical period for major congenital abnormalities. The adjusted odds ratio and the analysis of case-control pairs did not show any association between the rate of different congenital abnormalities and the corticosteroid treatment in the second and third months of gestation. Thus, treatments with corticosteroids in pregnancy do not appear to noticeably increase the risk of congenital abnormalities in humans.