High- vs standard-dose oxytocin better at reducing labour duration, chorioamnionitis risk

Administering a high-dose oxytocin regimen for labour augmentation falls short of reducing caesarean births, although it produces a marked reduction in labour duration and chorioamnionitis frequency, without deleterious effects on perinatal outcomes as compared with standard dosing, according to a study.

A total of 1,003 nulliparous women at or beyond 36 weeks of gestation were randomized to receive high-dose (initial and incremental rates of 6 milliunits/min; n=502) or standard-dose (initial and incremental rates of 2 milliunits/min; n=501) oxytocin regimens.

Most of the participants were White, were married or living as married, and had commercial insurance. Baseline characteristics between the treatment groups were similar.

Caesarean birth rates, the primary outcome, were similar: 14.5 percent in the high-dose group and 14.4 percent in the standard-dose group (relative risk [RR], 1.01, 95 percent confidence interval [CI], 0.75–1.37).

However, there were notable differences observed in prespecified secondary outcomes. Compared with standard-dose, high-dose oxytocin led to a shorter mean labour duration (9.1 vs 10.5 hours; p<0.001) and significantly lower chorioamnionitis incidence (10.4 percent vs 15.6 percent; RR, 0.67, 95 percent CI, 0.48–0.92).

Umbilical artery acidaemia likewise occurred less frequently in the high-dose group in complete case analysis, but this difference disappeared following multiple imputation (RR, 0.55, 95 percent CI, 0.29–1.04).

There were no significant differences in other secondary outcomes, including endometritis, postpartum haemorrhage, Apgar score ≤3 at 5 minutes, neonatal intensive care unit admission, perinatal death, and a severe perinatal morbidity composite.