Predicting factors for success of vaginal delivery in preterm induction with prostaglandin E(2)

OBJECTIVE: To evaluate the efficacy and safety of prostaglandin (PG) E(2) for preterm labor induction and to investigate the predictive factors for the success of vaginal delivery. METHODS: A retrospective cohort study was performed in women (n=155) at 24+0 to 36+6 weeks of gestation who underwent induction of labor using a PGE(2) vaginal pessary (10 mg, Propess) from January 2009 to December 2015. Success rates of vaginal delivery according to gestational age at induction and incidence of intrapartum complications such as tachysystole and nonreassuring fetal heart rate were investigated. Multivariable logistic regression analysis was performed to evaluate the predictive factors for success of labor induction. RESULTS: The vaginal delivery rate was 57% (n=89) and the rate of cesarean delivery after induction was 43% (n=66). According to gestational age, labor induction was successful in 16.7%, 50.0%, and 62.8% of patients at 24 to 31, 32 to 33, and 34 to 36 weeks, showing a stepwise increase (P=0.006). There were 18 cases (11%) of fetal distress, 9 cases (5.8%) of tachysystole, and 6 cases (3.8%) of massive postpartum bleeding (>1,000 mL). After adjusting for confounding factors, multiparity (odds ratio [OR], 8.47; 95% confidence interval [CI], 3.10 to 23.14), younger maternal age (OR, 0.84; 95% CI, 0.75 to 0.94), advanced gestational age at induction (OR, 1.06; 95% CI, 1.02 to 1.09), rupture of membranes (OR, 11.83; 95% CI, 3.55 to 39.40), and the Bishop score change after removal of PGE(2) (OR, 2.19; 95% CI, 1.0 to 4.8) were significant predictors of successful preterm vaginal delivery. CONCLUSION: An understanding of the principal predictive factors of successful preterm labor induction, as well as the safety of PGE(2), will provide useful information when clinicians consult with preterm pregnant women requiring premature delivery.