DOES LABOR START TOO LATE

To determine the optimal time of delivery, in terms of lowest risk of peripartum complications, the relative incidences of the parameters. A bnormal cardiotocogram (CTG), operative vaginal delivery, Apgar < 7 at 1 and 5 min, artery cord blood pH < 7.20, blood loss > 500 ml, epidur al anesthesia, and Cesarean section, were retrospectively analysed wit h regard to mode of labor onset (spontaneous, induced) and gestational age in all deliveries between gestational weeks (GW) 35 + 0/7 and 42 + 6/7 from 1986 through 1993 at Zurich University Hospital (n = 11,834 ), and additionally with regard to birth weight in the same population from 1987 through 1993 (n = 10,346). The distribution of most paramet ers was parabolic with nadirs at GW 37-38; the incidence of low Apgar scores and Cesarean sections, however, was lowest nearer term (GW 39-4 0). Mode of labor onset had little effect (less than or equal to 1 wee k) on the time of lowest incidence. The birth weight associated with t he fewest complications was 3000 g, with the optimal time of delivery being GW 37-38, assuming a birth weight normal for gestational age.