133 Association between simplified bishop score after cervical ripening and delivery outcome

A favorable Simplified Bishop Score (SBS>5) before induction of labor is associated with successful vaginal delivery. Unfavorable cervices (SBS≤5) undergo cervical ripening prior to administration of oxytocin. However, data is limited regarding the utility of the SBS after cervical ripening. The objective of this study is to determine if SBS prior to oxytocin induction, but after cervical ripening, is associated with vaginal birth. We conducted a retrospective cohort study on patients undergoing induction of labor from the NICHD Consortium on Safe Labor. Singleton term pregnancies who initially received cervical ripening agents were included. Patients with a history of cesarean were excluded. An SBS>5 after cervical ripening was compared to SBS≤5. Primary outcome was mode of delivery. Multivariate logistic regression was performed to control for variables, including admission SBS and parity. A total of 5,807 patients met criteria to be included in the study. 4,235 (73%) patients had an SBS≤5 and 1,572 (27%) patients had an SBS>5 after cervical ripening. The SBS≤5 group had more cesarean deliveries (32% vs 11%, p<0.0001). Both groups had low rates of maternal chorioamnionitis (4% vs 2%, p<0.0001). There was no significant difference in rates of postpartum hemorrhage, NICU admission, or birthweight. More cesarean deliveries among the SBS≤5 group persisted when stratifying by parity (nulliparous: 44% vs 18%; multiparous: 12% vs 2%, both p<0.0001). After controlling for maternal age, pre-pregnancy BMI, parity, gestational age, and SBS at admission, SBS≤5 remained significantly associated with more cesarean deliveries (aOR=2.52, 95% CI 1.98, 3.22). Starting oxytocin with SBS>5 after cervical ripening is associated with successful vaginal birth, even after adjusting for parity and admission SBS. Consideration of SBS after cervical ripening should be given prior to induction with oxytocin. However, further research is necessary to determine the ideal endpoint of cervical ripening.View Large Image Figure ViewerDownload Hi-res image Download (PPT)