High-dose versus low-dose of oxytocin for labour augmentation : a randomised controlled trial

Problem: Delayed labour progress is common in nulliparous women, often leading to caesarean section despite augmentation of labour with synthetic oxytocin. Background: High-or low-dose oxytocin can be used for augmentation of delayed labour, but evidence for promoting high-dose is weak. Aim: To ascertain the effect on caesarean section rate of high-dose versus low-dose oxytocin for augmentation of delayed labour in nulliparous women. Methods: Multicentre parallel double-blind randomised controlled trial (ClinicalTrials.gov: NCT01587625) in six labour wards in Sweden. Healthy nulliparous women at term with singleton cephalic fetal presentation, spontaneous labour onset, confirmed delay in labour and ruptured membranes (n = 1351) were randomised to labour augmentation with either high-dose (6.6 mU/minute) or low-dose (3.3 mU/minute) oxytocin infusion. Findings: 1295 women were included in intention-to-treat analysis (high-dose n = 647; low-dose n = 648). Caesarean section rates did not differ between groups (12.4% and 12.3%, 95% Confidence Interval -3.7 to 3.8). Women with high-dose oxytocin had: shorter labours (-23.4 min); more uterine tachysystole (43.2% versus 33.5%); similar rates of instrumental vaginal births, with more due to fetal distress (43.8% versus 22.7%) and fewer due to failure to progress (39.6% versus 58.8%). There were no differences in neonatal outcomes. Discussion: Our study could not confirm results of two systematic reviews indicating, with weak evidence, that use of high-dose oxytocin was associated with lower frequency of caesarean section. Conclusion: We found no advantages for routine use of high-dose oxytocin in the management of delay in labour. Low-dose oxytocin regimen is recommended to avoid unnecessary events of tachysystole and fetal distress.