Aspirin and congenital malformations.

In a cohort of 50 282 gravidas and their offspring in the U.S.A., malformation rates were similar in the children of 35 418 women not exposed to aspirin, 9736 with intermediate exposure, and 5128 women heavily exposed during the first four lunar months of pregnancy. After controlling a wide range of potential confounding factors using multi-variate analysis, the observed and expected numbers for a variety of malformation categories were similar in all three comparison groups. The data suggest that aspirin is not teratogenic.