Early Versus Delayed Oxytocin Augmentation in Nulliparous Women With Prolonged Labor—A Randomized Controlled Trial

Abstract

Some investigators believe that active management of labor with early amniotomy and oxytocin augmentation reduces the caesarean section rate, but this view has not been supported in several meta-analyses. Observational data have shown an association between use of oxytocin treatment in labors lasting less than 12 hours and adverse neonatal outcomes. This prospective randomized trial compared the effect of early and delayed intervention with oxytocin on obstetrical and neonatal outcomes in nulliparous women with spontaneous but prolonged labor at 3 Swedish delivery wards. The study subjects were healthy nulliparous women with normal pregnancies, a singleton fetus, spontaneous onset of active labor with regular contractions, an effaced cervix dilated between 4 and 9 cm, no progress in cervical dilatation for 2 hours and no further progress 1 hour after amniotomy. A total of 630 study women were randomized to either an early oxytocin group (infused within 20 minutes, n = 314) or to an expectant group (postponement of oxytocin infusion for 3 hours, n = 316). The primary study outcome was mode of delivery (spontaneous vaginal, instrumental vaginal, or caesarean). Primary analysis was according to intention to treat. No significant differences were found between the two treatment groups in the caesarean section rate: 29 of 314 (9.2%) in the early oxytocin group versus 34 of 316 (10.8%) in the expectant group (odds ratio [OR], 0.8; 95% confidence interval [CI], 0.5―1.6), or in the instrumental vaginal delivery rate: 54 of 314 (17.2%) in the early oxytocin group versus 38 of 316 (12%) in the expectant group (OR, 1.5; 95% CI, 0.97-2.4). The duration of labor was shortened by 90 minutes in the early oxytocin group compared to the expectant group (P < 0.001). No other differences in risk or benefit between the two study groups were observed. These findings are consistent with data from other studies showing that early use of oxytocin does not decrease the caesarean section rate but does reduce the duration of labor.