We studied the association between acetaminophen exposure during pregnancy and the prevalence of congenital abnormalities and fetal growth. Our study included 123 women who had received a prescription of acetaminophen during pregnancy and/or 30 days before conception and 13,329 controls who did not receive any prescription at all. We found more malformations among those who received a prescription with an odds ratio of 2.3 (95% CI 1.0-5.4), but the type of malformations did not indicate a causal link. When restricting the study to first time pregnancies, we identified 58 women who received a prescription of acetaminophen during pregnancy and 30 days before conception and 7472 controls. We found no excess risk of malformation [OR = 0.7 (95% CI 0.1-5.5)], and no evidence that acetaminophen should influence fetal growth.