Postdate pregnancy: utilization of contraction stress testing for primary fetal surveillance.

Six hundred seventy-nine postdate study patients surveyed with a contraction stress test (CST) protocol had no perinatal deaths and no greater morbidity than that found in a 500-patient normal term control population. However, the postdate study did have a significantly increased risk of intrapartum fetal distress, meconium-stained amniotic fluid, macrosomia, and cesarean section for both failed progress of labor and fetal distress. Among the postdate study group there was a high incidence of patients with abnormal CST results (39%); these patients with abnormal CST results were at increased risk for subsequent intrapartum fetal distress. Seventy-five percent of the postdate study patients entered labor spontaneously and delivery was elected because of abnormal CST results in only 5.4%. The data presented here support the use of contraction stress testing for primary surveillance of the prolonged pregnancy and they suggest that only one in 20 patients past 42 weeks' gestation will require intervention for fetal indications with this approach.