Maternal risk status and postdate pregnancy outcome.

Using a 1982-1985 regional perinatal network data base of 69,746 infants, a retrospective study was conducted to compare the perinatal outcome of 7,729 postdate infants (greater than or equal to 42 weeks' gestation) by maternal risk status. Due to additional antenatal complications, of which 8.0% were hypertension and/or diabetes, 48.4% of the postdate pregnancies were classified as at risk. As expected, high-risk women experienced a higher incidence of adverse perinatal outcomes than did low-risk women. The incidence of meconium staining, low five-minute Apgar scores and perinatal mortality increased beyond term and was found most commonly in infants from high-risk pregnancies, especially those involving hypertension and diabetes mellitus. These results suggest that high-risk pregnancies probably should not enter the postdate period since their doing so places the infant at serious risk.