Postdates pregnancy. Assessment of fetal risk and obstetric management.

Two hundred forty-eight well-dated pregnancies that exceeded their expected dates of confinement were followed with serial maternal urinary or plasma estriol determinations and weekly fetal heart rate tests. Most pregnancies (176) delivered after spontaneous labor, while 72 had labor induced for abnormal test results or electively. Perinatal mortality (8.1/1,000) was comparable to that of our term (37-40-week) population; the two deaths occurred in the 43rd week. Intrapartum fetal distress, meconium staining, postmaturity syndrome and primary cesarean section rates all increased with gestational age beyond the 40th week. Induced labors, irrespective of indication, were significantly longer than spontaneous ones and were associated with higher rates of fetal distress and primary cesarean section. In the study group, fetal distress often arose during labor and was not anticipated by the antenatal testing.