Cardiovascular birth defects and antenatal exposure to female sex hormones.

In a cohort of 50,282 pregnancies 19 children with cardiovascular defects were born to 1042 women who received female hormones during early pregnancy (18.2 per 1000). Among 49,240 children not exposed in utero to these agents there were 385 with cardiovascular malformations (7.8 per 1000). Six children with cardiovascular defects were born to a sub-group of 278 women who used oral contraceptives during early pregnancy (21.5 per 1000). After the data were controlled for a wide variety of potentially confounding factors by multivariate methods, the association between in utero exposure to female hormones and cardiovascular birth defects was statistically significant.