Comparing routine versus delayed amniotomy in spontaneous first labor at term. A multicenter randomized trial. UK Amniotomy Group

Abstract

Objective: To measure the effect of a policy of routine amniotomy on nulliparous labor.

Design: A multicenter randomized controlled trial.

Subjects: Nulliparous women (1463) in spontaneous labor at term with intact membranes and a single cephalic fetus.

Interventions: Rupturing membranes routinely early in labor or leaving them intact for as long as possible.

Main outcome measures: Duration of labor, operative and instrumental delivery rates, use of analgesia, perinatal death, neonatal convulsions, and admission to special care.

Results: Median duration of labor was 8.4 hours in the early rupture group and 9.4 hours in the late group. No clear trend for this difference emerged at any particular cervical dilatation at randomization. We found no difference in cesarean section, typical odds ratio (OR) 1.1 (95% CI, 0.65 to 1.8); operative vaginal delivery, OR 1.1 (95% CI, 0.83 to 1.5); use of epidural/spinal, OR 0.92 (95% CI, 0.72 to 1.2); use of pethidine, OR 1.0 (95% CI, 0.79 to 1.4); either method of analgesia, OR 0.96 (95% CI, 0.68 to 1.3); blood transfusion, OR 0.71 (95% CI, 0.28 to 1.8. We found no effect on fetal intubation, OR 1.40 (95% CI, 0.78 to 2.5), or on admission to special care, OR 1.28 (95% CI, 0.65 to 2.5). One fetus in the early amniotomy group had care, Or 1.28 (95% CI, 0.65 to 2.5). One fetus in the early amniotomy group had neonatal convulsions, but there were no perinatal deaths.

Conclusions: Beyond a modest shortening of labor, a policy of routine amniotomy has little effect on important outcomes and should not be recommended.