Preterm induction of labor: predictors of vaginal delivery and labor curves (original) (raw)

Objective-To evaluate the labor curves of patients undergoing preterm induction of labor (IOL) and assess possible predictors of vaginal delivery (VD). Study Design-Data from the NICHD Consortium on Safe Labor were analyzed. A total of 6,555 women undergoing medically-indicated IOL before 37 weeks gestational age (GA) were included in this analysis. Patients were divided into four groups based on gestational age: A: 24-27+6, B: 28-30+6, C: 31-33+6, and D: 34-36+6 weeks. Pregnant women with a contraindication to VD, IOL at or after 37 weeks and those without data from cervical exam on admission were excluded. ANOVA was used to assess differences between GA groups. Multiple logistic regression was used to assess predictors of VD. A repeated measures analysis was used to determine average labor curves. Results-Rates of vaginal live births increased with GA, from 35% (Group A) to 76% (Group D). Parous women [odds ratio (OR)=6.78, 95% confidence interval (CI) 6.38-7.21] and those with a favorable cervix at the start of IOL (OR=2.35, 95% CI 2.23-2.48) were more likely to deliver vaginally. Analysis of labor curves in nulliparous women showed shorter duration of labor with increasing GA; the active phase of labor was, however, similar across all GA.