Comparison of Maternal and Infant Outcomes From Primary Cesarean Delivery During the Second Compared With First Stage of Labor

Abstract

About 1 in 4 primary cesarean deliveries take place during the second stage of labor. Not only is second-stage surgery technically more difficult, but the fetus is at risk of hypoxia-related morbidity. This prospective observational study of primary cesarean deliveries was carried out at 13 university centers that make up the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Of 11,981 primary cesarean deliveries, 9265 were done in the first and 2716 in the second stage of labor. Women in the latter group were likely to be older, nulliparous, and white, and they had a smaller body mass index at the time of delivery. In both groups, dystocia was the commonest indication for cesarean delivery. Second-stage deliveries were significantly longer than those done in the first stage of labor. Intraoperative complications were significantly more frequent when cesarean section was done in the second stage of labor because of higher rates of uterine atony, extension of a “T” or “J” uterine incision, and cystotomy. Women delivered in the second stage had slightly larger infants. Fetal injuries were more common in the second-stage group, but more infants in the first-stage group were admitted to intensive care for 24 hours or longer. The maternal composite index (endometritis, intraoperative surgical complications, blood transfusion, and/or wound complications) was slightly increased when cesarean section was done in the second stage of labor. The difference was significant after multivariable analysis, with an odds ratio of 1.21 and a 95% confidence interval of 1.07–1.37. In contrast, the neonatal composite outcome (5-minute Apgar score of 3 or less, neonatal death, admission to neonatal intensive care, intubation in the delivery room in the absence of meconium, and/or fetal injury) did not differ significantly between the 2 groups after multivariable analysis. Maternal—but not neonatal—morbidity appears to be marginally increased when primary cesarean section is performed in the second rather than in the first stage of labor. The investigators believe that a trial of labor extending into the second stage does not in itself increase the risk of an adverse maternal or neonatal outcome.