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A cross-sectional analytic survey of 92 patients permitted to attempt vaginal delivery after previous lower segment cesarean section ("trial of scar") is reported. Variables which may predict mode of delivery were assessed. Fifty patients (54.3%) were delivered vaginally; 42 patients (45.7%) had repeat cesarean sections in labor. There were three cases of scar dehiscence (3.2%). There were no maternal or fetal mortality. When the cervix was less than 3 cm dilated at initial examination in labor, 10 of 37 patients (27%) were delivered vaginally, compared to 38 of 55 patients (69%) who were delivered vaginally when the cervix was greater than 3 cm dilated. Assessment of cervical dilatation on admission in labor proved to be the most significant prognostic factor at the onset of labor, with regard to successful vaginal delivery in a patient with a lower segment cesarean section scar.

The perinatal mortality rate among very low-birth weight infants has been decreased by 20% during the last 4 years of the 1973 to 1980 period here reported. The concurrent increase in the cesarean section rate from 11.9% to 49.1% during the same time frames has been assumed to be responsible for the improved outcome. The changes were most marked in the extremely low-birth weight group (less than 1,000 gm). The survival rates and cesarean section rates were examined among infants of similar birth weight and gestational age in the vertex presentation, in the same time frames. A similar or greater reduction in mortality rate (from 85% to 45%) was noted in the very low-birth weight vertex infants, whereas the cesarean section rate remained minimally and not significantly increased (14.2% to 22.2%). The interpretation of this finding is by no means clear but must include the hypothesis that the increased cesarean section rate may be incidental and in no way related to the improved outcome. The most statistically significant determinants of outcome remain birth weight and gestational age strata, with no significant difference in outcomes when the extremely low-birth weight group is analyzed separately from the entire very low-birth weight group. As yet unidentified perinatal care practices, other than cesarean section, may be more likely to affect outcome in this high-risk group.

A descriptive study of 300 consecutive spontaneous labors in primigravid patients whose pregnancies were of 37 or more weeks' gestation with a singleton fetus in the vertex presentation, showed a cesarean section rate of 13%, a forceps delivery rate of 49%, and a spontaneous delivery rate of 38%. Oxytocin was used in 17% and epidural analgesia was used in 75% of the patients. The median rate for cervical dilatation for those women with spontaneous deliveries was 2 cm/hr (interquartile range = 1.5 to 3.3 cm/hr) and for those delivered with forceps, 1.2 cm/hr (interquartile range = 0.9 to 1.8 cm/hr). When labor was prolonged by 4 hours or more, the cesarean section rate rose to 34%. Oxytocin was used in only 41% of these patients. Of 23 women delivered by cesarean section for dystocia/disproportion, only nine received oxytocin. From the low incidence of low Apgar scores in all labor groups from this series, there would not appear to be a fetal advantage to earlier intervention. Although the suggestion from this study is that oxytocin administration when labor is prolonged by 4 hours will reduce the need for cesarean section, the true value of such an intervention can be tested only by a randomized controlled trial.