404: Outcomes after non-indicated induction of labor compared to expectant management: An observational study

Abstract

Despite limited evidence about the risks or benefits of non-indicated (elective) induction of labor, many healthcare systems have launched initiatives to reduce its use. Great uncertainty remains about the outcomes of elective induction, including whether the impact differs at different gestational ages. To address these research gaps, this study examined the association between elective induction of labor, compared to expectant management, and subsequent maternal and neonatal outcomes. We conducted a two-phase observational study at two integrated healthcare delivery systems, Kaiser Permanente Washington and KP Southern California. Electronic health plan and linked birth certificate data provided information about nulliparous women with a singleton birth from 2007-2013 who as of 38 weeks’ gestation did not have an indication for induction or a contraindication to vaginal delivery. We next used these electronic data to classify women’s apparent exposure and outcome status and then sampled a subgroup for medical record review to confirm eligibility, validate exposure and outcome status, and ascertain covariates. We oversampled women with apparent elective induction and study outcomes (listed in Table). Women undergoing elective induction at a given gestational age (38, 39 or 40 weeks) were compared with those managed expectantly at that age, accounting for sampling and adjusting for covariates via semiparametric maximum likelihood estimation, generating odds ratios and 95% confidence intervals. From a population of 43,378 eligible women, we reviewed medical records for 3,183. There were 36, 78, and 243 deliveries sampled with confirmed elective induction at 38, 39, and 40 weeks gestation, respectively. Results (see Table) indicated that elective induction at 39 weeks was associated with 64% higher odds of cesarean delivery than expectant management, while elective induction at 40 weeks was associated with 38% lower odds of neonatal intensive care unit admission but 48% higher odds of chorioamnionitis. Elective induction at 39 weeks gestation may increase the likelihood of cesarean delivery, while it may reduce NICU admission at 40 weeks’ gestation. Next steps to advance understanding of elective induction should include observational studies with larger sample size or a large randomized trial.