The association between delayed amniotomy and adverse outcomes in labor induction

To assess if delayed amniotomy during labor induction is associated with adverse delivery outcomes.

Retrospective cohort study of women with a viable, singleton gestation who underwent labor induction at a tertiary-care hospital (4/2014-3/2017). Women were excluded if oxytocin was not used or if spontaneous rupture of membranes (ROM) occurred ≤8 h after oxytocin initiation. The primary outcome was cesarean delivery, and secondary outcomes included postpartum hemorrhage, maternal infectious morbidity, neonatal 5-min Apgar score <7, and neonatal intensive care unit admission. Women were compared by timing of amniotomy: delayed (ROM > 8 h after oxytocin initiation) versus not delayed. Multivariable logistic regression was used to estimate the association between delayed amniotomy and study outcomes.

Of 2081 women who met inclusion criteria, 1125 (before 54%) had delayed amniotomy. Women with delayed amniotomy had ROM 12.7 h (IQR 10.0, 17.9) after oxytocin versus 5.0 h (IQR 3.7, 6.5) without delayed amniotomy. In multivariable regression, delayed amniotomy was associated with increasingly higher odds of cesarean as maternal obesity severity increased (aOR 1.58, 95 %CI 1.24-2.03 at BMI 30 kg/m²; aOR 2.15, 95 %CI 1.45-3.21 at BMI 40 kg/m²; aOR 2.93, 95 %CI 1.54-5.57 at BMI 50 kg/m²).

Delayed amniotomy >8 h after starting oxytocin for labor induction was associated with higher odds of cesarean delivery. Significant delay in ROM should be avoided during labor induction.