A population-based case-control teratologic study of oral erythromycin treatment during pregnancy.

The objective of the study was to evaluate the human teratogenic potential of oral erythromycin treatment during pregnancy in the population-based dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. Of 38,151 pregnant women who had newborn infants without any congenital abnormalities (population control group), 172 (0.5%) had received erythromycin, while of 22,865 pregnant women who had newborns or fetuses with congenital abnormalities, 113 (0.5%) had been treated with erythromycin (crude OR with 95% Cl = 1.1, 0.9-1.4). The case-control pair analysis did not indicate a teratogenic potential of erythromycin during the second through third months of gestation, i.e., in the critical period for most major congenital abnormalities. The frequency of maternal erythromycin treatments during the second-third months of pregnancy was also not higher in different congenital abnormality groups compared with the rate of the total control group as referent. Thus, treatment with oral erythromycin during pregnancy did not present detectable teratogenic risk to the fetus.