Perinatal characteristics of uncomplicated postdate pregnancies.

Using a regional perinatal network database of 60,456 births, a study compared 3457 postdate (42 weeks or longer) infants to a control group of 8135 infants born at 40 weeks' gestation from 1982 through 1985. Both patient groups included only uncomplicated pregnancies. Although the differences were small, women who delivered postdate infants had a lower parity, higher weight at delivery, and higher blood pressure during pregnancy than controls. The postdate infants were heavier, more likely to be delivered by forceps or cesarean section, and more likely to experience shoulder dystocia. They also had lower Apgar scores and more meconium aspiration and congenital malformations. Although the overall perinatal mortality was not statistically different, the higher perinatal morbidity in postdate infants suggests that careful attention should be paid to this high-risk problem.