Assessing the impact of indication for labor induction on delivery outcomes: a five-year cohort study

As the rate of induction of labor (IOL) is steadily increasing with the increasing rates of maternal age and obesity, having consequences on perinatal morbidity, health economics, and maternal childbirth experience, evidence for decision making should be available related to the indications. This study investigates the association of IOL indications with the delivery outcomes and provides clinicians with valuable information to weigh the benefits and potential risks associated with IOL.

This retrospective five-year cohort study was conducted in Helsinki University Hospital between 2017 and 2021. A total of 16 377 pregnant women undergoing IOL ≥ 37 gestational weeks with a live singleton fetus in cephalic presentation were included. The primary outcome measures were the rates of cesarean delivery (CD) and composite adverse neonatal outcome (including one or more of the following: perinatal death, neonatal intensive care admission, umbilical artery blood pH value ≤ 7.05, base excess value <-12, and 5-minute Apgar score 0-6).

The study population consisted of 16 377 women. The most common indications for IOL were post-term pregnancy (31.3%) and pre-labor rupture of membranes (PROM) (26.3%). Overall, the CD rate was 20.3%, and the incidence of composite adverse neonatal outcome was 12.7%. Delivery outcomes varied according to the indication for induction. The highest CD rate of 27.9% was observed among women induced for hypertensive disorders (adjusted OR 1.6, 95% CI 1.4-1.8), whereas inductions for maternal exhaustion were associated with the lowest CD rate. Composite adverse neonatal outcomes were most frequent (19.1%, n = 179) following induction for fetal indications and least frequent (7.4%, n = 42) among women induced because of fear of childbirth. In analyses, performed separately for each IOL indication, nulliparity, unfavorable cervix, maternal age ≥ 35 years, maternal height < 164 cm, and pre-pregnancy BMI ≥ 30 remained independent risk-factors for CD.

The indication for IOL is associated with both CD and adverse neonatal outcomes. While indication-specific differences should be considered when counseling women and planning induction, maternal characteristics and parity remain important determinants of CD risk. These findings may support individualized clinical decision-making regarding IOL.