Induction of labor: does indication matter?

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. 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 aecurrency sign7 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). 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. The indication for induction of labor may impact its failure rate.