Predictors of response after a second attempt of pharmacological labor induction: a retrospective study

Purpose: The aim of our study was to assess the outcomes of a prolonged induction carried out with a second sequential cycle of pharmacological stimulation after unsatisfactory response to a first attempt, and to highlight variables correlated with higher response rates. Methods: A retrospective study was carried out on 157 women who underwent a two-step labor induction by vaginal prostaglandins followed by a second cycle of prostaglandins or intravenous oxytocin. Outcomes assessed were mode of delivery and maternal and neonatal morbidity. Main variables of pregnancy and delivery were collected to identify factors predicting the mode of delivery. Results: Among 157 patients, 63 (40.1%) achieved a vaginal delivery, whereas 94 (59.9%) underwent Cesarean section, 9 women (5.7%) had postpartum hemorrhage; in 2 cases (1.3%), an Apgar score < 7 at 5 min from birth was reported. Higher risk of Cesarean section was observed with advanced maternal age (OR 1.13 for additional year, CI 1.04–1.22) and nulliparity (OR 8.84, CI 2.69–29.06), whereas the response rates were better in carriers of group B streptococcus colonization (OR 0.38, CI 0.17–0.84) and in women with favorable cervical status after the first stimulation (OR 0.81 for additional point of Bishop score, CI 0.70–0.94). Conclusion: Labor induction with two cycles of pharmacological stimulation is a procedure with fairly good success rates and a low risk of maternal and neonatal complications. Factors predicting its success encompass younger age, parity, a positive recto-vaginal swab for group B streptococcus and a favorable cervix following the first cycle of stimulation.