A randomized trial of induction at 42 weeks gestation versus expectant management for postdates pregnancies.

A randomized prospective clinical trial of induction of labor at 42 completed weeks gestation versus expectant management in postdates pregnancies was performed. The primary screening test was the 24-hr urinary estriol creatinine ratio. The cesarean section rate was high in both groups and did not differ statistically. Intervention by delivery at 42 weeks decreased the development of small for gestational age infants, but costs slightly more. Twenty-four-hour urinary estriol creatinine ratio determinations predicted fetal distress in labor, but could not predict postmaturity syndrome or infants who were small for gestational age. As expectant management did not differ from induction of labor at 42 weeks from the standpoint of maternal outcome, and as the cost difference was small, induction of labor at 42 weeks may be the preferred management as it improves infant outcome.