Objective: To study the effects of early versus delayed oxytocin augmentation on the obstetrical and neonatal outcome in nulliparous women with spontaneous but prolonged labour.
Design: Randomised controlled study.
Setting: Two delivery units in Sweden.
Population: Healthy nulliparous women with normal pregnancies, spontaneous onset of active labour, a cervical dilatation of 4-9 cm and no progress in cervical dilatation for 2 hours and for an additional hour if amniotomy was performed due to slow progress.
Methods: Women (n = 630) were randomly allocated either to labour augmentation by oxytocin infusion (early oxytocin group) or to postponement of oxytocin augmentation for another 3 hours (expectant group).
Main outcome measure: Mode of delivery (spontaneous vaginal or instrumental vaginal delivery or caesarean section) and time from randomisation to delivery.
Results: The caesarean section rate was 29 of 314 (9%) in the early oxytocin group and 34 of 316 (11%) in the expectant group (OR 0.8, 95% CI 0.5-1.4), and instrumental vaginal delivery 54 of 314 (17%) in the early oxytocin versus 38 of 316 (12%) in the expectant group (OR 1.5, 95% CI 0.97-2.4). Early initiation of oxytocin resulted in a mean decrease of 85 minutes in the randomisation to delivery interval.
Conclusion: Early administration of oxytocin did not change the rate of caesarean section or instrumental vaginal delivery but shortened labour duration significantly in women with a 2-hour arrest in cervical dilatation. No other clear benefits or harms were seen between early and delayed administration of oxytocin.