Factors Associated with Intrapartum Cesarean Section in Women Submitted to Labor Induction

To evaluate the results of induced labor and to determine the main factors associated with intrapartum cesarean section after patients being submitted to this procedure at the Hospital Universitário of the Universidade Federal de Santa Catarina (HU/UFSC, in the Portuguese acronym), Florianópolis, state of Santa Catarina, Brazil. A retrospective cross-sectional study that included all the pregnancies that resulted in single-fetus births, whose gestational-age was > 22 weeks and that had been submitted to labor induction at the HU/UFSC in the period from 2013 to 2016. During the proposed period, 1,491 pregnant women were submitted to the labor induction protocol. In 1,264 cases (84.8%), induction resulted in labor, with 830 (65.7%) progressing to vaginal delivery. Gestational age ≥ 41 + 0 weeks was the most common indication for induced labor (55.2%), and vaginal administration of misoprostol was the most commonly used method (72.0%). Among these pregnant women, the cesarean section rate was of 34.3%. Considering the cases of induction failure, the cesarean section rate rose to 44.3%. The factors associated with cesarean section were: previous history of cesarean delivery (PR [prevalence ratio] = 1.48; 95%CI [confidence interval]: 1.51-1.88), fetuses with intrauterine growth restriction (IUGR) (PR = 1.82; 95%CI: 1.32-2.19), Bishop score ≤ 6 (PR = 1.33; 95%CI: 1.01-1.82), and induction time either 36 hours (PR = 1.51; 95%CI 1.22-1.92) between the beginning of the induction and the birth. Labor induction was successful in most patients. In the cases in which the final outcome was a cesarean section, the most strongly associated factors were: previous history of cesarean delivery, presence of fetuses with IUGR, and either excessively short or excessively long periods of induction.