Induction of labor: does indication matter?

Purpose: Labor induction is performed in 20 % of pregnancies. However, the impact of the indications for induction on its failure rate has hardly been investigated. We aimed to evaluate the association of indications for labor induction with failure rate. Methods: Background and delivery-related data were retrospectively collected for all women with a viable term singleton pregnancy, who underwent labor induction with a PGE2 vaginal insert in 2013–2014. Reasons for induction were categorized as maternal indications, hypertensive disorders, premature rupture of membranes, and fetal indications. Induction failure was defined as Bishop score ≤7 at 24 h after PGE2 administration, cesarean delivery due to latent phase dystocia or removal of the insert due to non-reassuring fetal heart rate followed by emergency cesarean delivery. Outcome measures were rate of induction failure (primary) and rate of cesarean delivery (secondary). Results: The cohort included 1066 women. Those who failed induction (n = 213, 20 %) were more likely to be nulliparous (69.5 vs. 45.7 %, p < 0.0001), older (31 vs. 30 years, p = 0.047), and at an earlier gestational age (39.4 vs. 40.0 weeks, p < 0.0001). Among nulliparous women, maternal indications were significantly associated with induction failure (aOR 2.52, 95 % CI 1.28–4.95, p = 0.007) and cesarean delivery (aOR 2.36, 95 % CI 0.40–2.29, p = 0.019). Among multiparous women, hypertensive disorders (aOR 7.26, 95 % CI 1.89–27.87, p = 0.004) and maternal indications (aOR 4.22, 95 %CI 1.14–15.58, p = 0.031) were significantly associated with induction failure but not cesarean delivery. Conclusions: The indication for induction of labor may impact its failure rate.