Risk factors and ramifications of failure to achieve cervical ripening with prostaglandins -- Retrospective Cohort Study

Objective: To assess the characteristics and evaluate the outcomes of women who failed to respond to cervical ripening with prostaglandins. Methods: A retrospective cohort analysis (2012-2018) of all women with singleton gestation who underwent induction of labor, due to post-date pregnancy, with a slow-release prostaglandin-E2 vaginal insert for cervical ripening. Overall, 1285 women were divided into 2 groups: a) responders - 1,202 (93.54%) - achieved ripening within 24 hours ; b) non-responders- 83 (6.46%) – did not achieve cervical ripening within 24 hours. Characteristics and outcomes were compared between the groups. Primary outcome was defined as vaginal delivery rate following ripening process. Secondary outcomes were defined as composite adverse maternal and adverse neonatal outcomes. A model combining maternal characteristics and response rates to ripening was constructed as well. Results: In comparison to non-responders, responders achieved higher rates of vaginal delivery (96.51% vs. 66.27%, p<0.001). They also had lower rates of adverse maternal outcomes (12.81% vs. 24.10%, p=0.031) and of neonatal respiratory adverse outcomes (1.33% vs. 6.02%, p=0.009). The responders were also younger (30.03 vs 31.73, p=0.005), and less nulliparous (76.92% vs 50.99%, p<0.001). A multivariate analysis showed that failure to achieve a cervical ripening is an independent risk factor for intrapartum cesarean delivery due to failure to progress in labor (aOR 11.90, 95% CI 6.13-23.25). Conclusion: Women who achieve cervical ripening with PROPESS are younger, and more often multiparous. This group is associated with lower rates of intrapartum cesarean delivery and adverse outcomes.