Maternal and neonatal risk factors for cryptorchidism.

We assessed risk factors for cryptorchidism in a prospective hospital-based cohort study at Mount Sinai Hospital in New York City. We examined at birth 6,699 singleton male neonates who were delivered between October 1987 and October 1990. Follow-up examinations were undertaken at 3 months and 1 year for those diagnosed as cryptorchid at birth. We calculated prevalence ratios and adjusted odds ratios according to selected maternal and neonatal characteristics for those who remained cryptorchid at the 1-year assessment. We found elevated risks for maternal obesity [prevalence ratio = 2.42; 95% confidence interval (CI) = 1.11-5.27], for infants delivered by cesarean section (adjusted odds ratio = 2.17; 95% CI = 1.29-3.65), for low birthweight (adjusted odds ratio = 2.29; 95% CI = 1.12-4.70), for preterm birth (adjusted odds ratio = 2.25; 95% CI = 1.16-4.35), and for infants with congenital malformations (prevalence ratio = 13.97; 95% CI = 1.27-26.67). We observed a seasonal effect, with a peak in births of cryptorchid infants during September through November and a smaller peak during the months of March through May. We found no evidence that young women, white women, or primiparas were at increased risk.