Continued versus discontinued oxytocin stimulation in the active phase of labour (CONDISOX): double blind randomised controlled trial

Objective: To determine whether discontinuing oxytocin stimulation in the active phase of induced labour is associated with lower caesarean section rates.

Design: International multicentre, double blind, randomised controlled trial.

Setting: Nine hospitals in Denmark and one in the Netherlands between 8 April 2016 and 30 June 2020.

Participants: 1200 women stimulated with intravenous oxytocin infusion during the latent phase of induced labour.

Intervention: Women were randomly assigned to have their oxytocin stimulation discontinued or continued in the active phase of labour.

Main outcome measure: Delivery by caesarean section.

Results: A total of 607 women were assigned to discontinuation and 593 to continuation of the oxytocin infusion. The rates of caesarean section were 16.6% (n=101) in the discontinued group and 14.2% (n=84) in the continued group (relative risk 1.17, 95% confidence interval 0.90 to 1.53). In 94 parous women with no previous caesarean section, the caesarean section rate was 7.5% (11/147) in the discontinued group and 0.6% (1/155)in the continued group (relative risk 11.6, 1.15 to 88.7). Discontinuation was associated with longer duration of labour (median from randomisation to delivery 282 v 201 min; P<0.001), a reduced risk of hyperstimulation (20/546 (3.7%) v 70/541 (12.9%); P<0.001), and a reduced risk of fetal heart rate abnormalities (153/548 (27.9%) v 219/537 (40.8%); P<0.001) but rates of other adverse maternal and neonatal outcomes were similar between groups.

Conclusions: In a setting where monitoring of the fetal condition and the uterine contractions can be guaranteed, routine discontinuation of oxytocin stimulation may lead to a small increase in caesarean section rate but a significantly reduced risk of uterine hyperstimulation and abnormal fetal heart rate patterns.

Trial registration: ClinicalTrials.gov NCT02553226.