Can we predict successful cervical ripening with prostaglandin E2 vaginal inserts?

Previous studies have suggested that a variety of maternal and obstetrical characteristics may predict successful prostaglandin E2 (PGE2) cervical ripening. However, in most studies women were administered vaginal tablets or gel so scarce is known regarding potential predictors in women administrated slow-release vaginal inserts. We aimed to characterize the response of cervical ripening for labor induction using slow-release PGE2 vaginal insert and to identify predictors for success.

A retrospective cohort study in a single center (2013-2015). The association between maternal characteristics at admission and cervical ripening success/failure were explored. Cervical ripening failure was defined as a Bishop's score <7 following 24 h from cervical ripening or the need for cesarean delivery (CS) due to arrest of dilatation at cervical dilatation ≤5 cm. Cases with major fetal anomalies, multiple gestations, non-vertex presentation or any contraindication for vaginal delivery were excluded.

Of 15,564 deliveries during the study period, 986 (6.3%) women met inclusion criteria, of them, 774 (78.56%) succeeded and 212 (21.5%) failed cervical ripening. Cervical ripening success was associated with (OR, 95% CI): nulliparity (0.42, 0.22-0.81, p = 0.009, i.e., nulliparity was negatively associated with successful ripening), gestational age (GA) at delivery (1.29, 1.02-1.61, p < 0.03), and cervical dilation at admission (4.58, 2.57-8.17, p < 0.001). The indications for labor induction were not associated with cervical ripening success. A prediction model which included the abovementioned characteristics had an AUC of 0.792 (95% CI 0.743-0.840).

Overall, basic parameters, such as parity, cervical dilatation at admission and gestational age can predict successful cervical ripening PGE2 vaginal inserts.