High-dose compared with low-dose oxytocin for induction of labour of nulliparous women at term.

BACKGROUND: The optimal oxytocin infusion regimen to induce labour with the lowest caesarean section rate, instrumental delivery rate and length of active labour is unclear. We compared the effect of a low-dose to high-dose oxytocin regimen to induce labour.

MATERIALS AND METHODS: We conducted a retrospective study of nulliparous women induced at term in a single tertiary centre from 2009 to 2015. The oxytocin induction protocol changed from a high to low-dose regimen in November 2012, affording us the opportunity to compare outcomes 3 years prior to, and following the change in protocol. Main outcome measures were caesarean section rate, instrumental delivery rate and length of active labour.

RESULTS: Four thousand eight hundred and eighty-five participants were included, 2211 were induced via the low-dose regimen, and 2674 using the high-dose regimen. There was no difference in caesarean section rate (adjusted OR 0.99; 95% CI 0.87-1.13) or instrumental delivery rates once adjusted for regional anaesthesia (adjusted OR 1.16; 95% CI 0.99-1.36) between the different regimens. Surprisingly, the length of labour was longer in the high-dose oxytocin group (adjusted mean difference 0.60 h; 95%CI 0.81-0.12). There were significantly more postpartum haemorrhage ≥1000 ml (10.5% versus 7.8%, p < .001) and regional anaesthesia use (55.8% versus 52.1%, p = .03) in the low-dose cohort. There were no differences in neonatal outcomes.

CONCLUSION: Outcomes between high- and low-dose oxytocin induction regimens are relatively comparable with similar caesarean section and instrumental delivery rates. Therefore, either regimen is acceptable for use for induction of labour.