Birth defects in relation to threatened abortion.

The evidence for the association between threatened abortion and birth defects is limited and inconsistent. This study examined this relation using data from the Shanghai Birth Defects Monitoring Program. A total of 1,013 cases of birth defects and an equal number of controls were analyzed. Our study showed that women with threatened abortion had a 50% higher risk of having a baby with birth defects compared with those without this complication, controlling for other factors (adjusted odds ratio = 1.5; 95% confidence interval = 1.1-2.1). Threatened abortion was generally related to defects of the urogenital system, heart and circulatory system, and musculoskeleton and limbs and was specifically associated with polydactyly, undescended testicle, and hypospadias.