Objective: To estimate when rates of pregnancy complications increase beyond 37 weeks of gestation.
Methods: We designed a retrospective, cohort study of all women delivered beyond 37 weeks of gestational age from 1992 to 2002 at a single community hospital. Rates of perinatal complications by gestational age were analyzed with both bivariate and multivariable analyses. Statistical significance was designated by P <.05.
Results: Among the 45673 women who delivered at 37 completed weeks and beyond, the rates of meconium and macrosomia increased beyond 38 weeks of gestation (P <.001), the rates of operative vaginal delivery, chorioamnionitis, and endomyometritis all increased beyond 40 weeks of gestation (P <.001), and rates of intrauterine fetal death and cesarean delivery increased beyond 41 weeks of gestation (P <.001).
Conclusion: Risks to both mother and infant increase as pregnancy progresses beyond 40 weeks of gestation.