The association between delayed amniotomy and adverse outcomes in labor induction.

Objective: To assess if delayed amniotomy during labor induction is associated with adverse delivery outcomes.
Study Design: 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.
Results: 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/m ² ; aOR 2.15, 95 %CI 1.45-3.21 at BMI 40 kg/m ² ; aOR 2.93, 95 %CI 1.54-5.57 at BMI 50 kg/m ² ).
Conclusion: 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.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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