Does Induction of Labor Increase the Risk for Cesarean Section?

Abstract

Rising rates of cesarean delivery are a major concern for all medical professionals. Reducing the frequency of induction is often mentioned as a means to reverse this trend. Published studies and review articles have examined induction of labor (IOL) versus expectant management and the risk for cesarean delivery, with conflicting results. This systematic review and meta-analysis was performed to determine whether IOL compared with expectant management in women with intact membranes increased the rate of cesarean delivery. MEDLINE, EMBASE, and the Cochrane Database of Clinical Trials were searched. Studies were included if IOL, for indications other than premature rupture of membranes, was compared with expectant management and outcome data on route of delivery were provided. Quantitative analyses with fixed- and random-effects models were performed. Of 1368 unique citations, the review included 37 studies; 27 were induction trials of uncomplicated pregnancies at 37 to 42 weeks of gestation and 10 evaluated IOL versus expectant management in pregnancies with suspected macrosomia, gestational diabetes, oligohydramnios, twins, intrauterine growth restriction, and mild gestational hypertension as well as in women with a high risk score for cesarean delivery. The reported overall cesarean delivery rates varied from 1% to 47%. In almost all studies, IOL was necessary in many of the expectantly managed patients, with rates of 4% to 50%. Most trials reported that the time to delivery increased by approximately 1 week in the expectantly managed group versus the IOL group. Nineteen trials were evaluated to be of high quality; and 17, of low quality. A quantitative summary analysis combined results of 31 trials, with 6248 and 5917 women randomized to IOL and expectant management, respectively. Induction of labor was associated with a reduction in the risk for cesarean delivery compared with expectant management (odds ratio [OR], 0.83; 95% confidence interval [CI], 0.76–0.92). The reduced risk for cesarean delivery was seen in both subgroups of the trials, specifically those examining IOL in women with late-term and postterm gestations (OR, 0.85; 95% CI, 0.76–0.95), and in the trials of IOL for other indications (OR, 0.81; 95% CI, 0.69–0.95). Subgroup analysis of only the 19 high-quality trials revealed a similar result (OR, 0.82; 95% CI, 0.73–0.91). Meta-analysis of the risk for cesarean delivery for fetal distress or the outcomes of postpartum hemorrhage and operative vaginal delivery did not find an increase with IOL. In addition, no statistically significant differences were seen between IOL and expectant management for Apgar score of less than 7 at 5 minutes, admission to the neonatal intensive care unit, or perinatal death. Induction of labor is associated with a moderate but statistically significant reduction in the risk for cesarean delivery. Differences in other maternal and neonatal outcomes were not apparent. On the basis of these findings, it may be that women at high risk for cesarean delivery (older age or obese) could benefit from elective induction. This should be investigated in further clinical trials.