The impact of extending the second stage of labor to prevent primary cesarean delivery on maternal and neonatal outcomes.

BACKGROUND: A low rate of primary cesarean delivery is expected to reduce some of the major complications that are associated with a repeat cesarean delivery, such as uterine rupture, adhesive placental disorders, hysterectomy, and even maternal death. Since 2014, and in alignment with the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine, we changed our approach to labor dystocia, defined as abnormal progression of labor, by allowing a longer duration of the second stage of labor.

OBJECTIVE: To examine the effect of prolonging the second stage of labor on the rate of cesarean delivery, and maternal and neonatal outcomes.

MATERIALS AND METHODS: In a historical control group, we compared maternal and neonatal outcomes over 2 periods. Period I (9300 patients): from May 2011 until April 2014, when a prolonged second stage in nulliparous women was considered after 3 hours with regional anesthesia or 2 hours if no such anesthesia was provided. Second-stage arrest was defined in multiparous women after 2 hours with regional anesthesia or 1 hour without it. Period II (10,531 patients): from May 2014 until April 2017, allowed nulliparous and multiparous women continuing the second stage of labor an additional 1 hour before diagnosing second-stage arrest. Singleton deliveries at or beyond 37 weeks' gestation were initially considered for eligibility. We excluded women with high-risk pregnancies and known fetal anomalies. For comparing means, we used the t test. If variables were not normally distributed, we used the Mann-Whitney test instead. For comparing proportions, we used the χ2 test with continuity correction.

RESULTS: The primary cesarean delivery was decreased in nulliparous women from 23.3% (819 of 3515) in period I to 15.7% (596 of 3796) in period II (relative risk [RR], 0.67; 95% CI, 0.61-0.74), a trend that was also significant in multiparous women (10.9%, 623 of 5785, in period I vs 8.1%, 544 of 6735, in period II; RR, 0.75; 95% CI, 0.67-0.84). The rate of operative vaginal deliveries in nulliparous women was higher in period II than in period I (19.2%, 732 of 3515, vs 17.7%, 622 of 3796, P < .0001). Rates of third- and fourth-degree laceration and of shoulder dystocia were also higher in period II. The rate of arterial cord pH < 7.0 and the rate of admission to the neonatal intensive care unit were higher in period II, but the early neurological outcome was not different when comparing the 2 periods.

CONCLUSION: The new policy of labor management successfully decreased primary cesarean deliveries, with a small rise in instrumental deliveries. However, it also increased the other immediate maternal and neonatal complications. A higher rate of lower umbilical artery cord pH was the most significant finding; however, the early neurological outcome did not change. It is possible that the ongoing adjustment to the new labor protocol will avoid, in the future, maternal and neonatal complications. The long-term maternal and neonatal consequences of our new approach will be evaluated in future studies.