Continued versus discontinued oxytocin stimulation in the active phase of induced labour: Factors associated with unexpectedly high rates of conversion to open label oxytocin in the CONDISOX trial

Objective: To examine the factors associated with unexpectedly high rates of conversion to open label oxytocin in the CONDISOX trial of continuation versus discontinuation of oxytocin infusion during induced labour.Design: Secondary retrospective analysis of data from a prospective randomised controlled trial.Setting: Nine hospitals in Denmark and one in the Netherlands between 8 April 2016 and 30 June 2020.Population or sample: 1200 women having labour induced.Methods: Analysis of outcomes by actual management.Main outcome measures: Mode of delivery and associated variables.Results: Switching to open label oxytocin (42.4% overall) was associated with nulliparity, an unripe cervix, larger babies and higher rates of delivery by caesarean section.Conclusions: In the CONDISOX trial, slow labour was associated with features suggesting a higher 'resistance to progress', often prompting the use of open-label oxytocin infusion rather than study medication.