A randomised controlled trial of amniotomy and immediate oxytocin infusion versus amniotomy and delayed oxytocin infusion for induction of labour at term.

BACKGROUND: There is uncertainty as to the optimal time interval between amniotomy and oxytocin administration when inducing labour. The aim of this study was to compare the efficacy of amniotomy and immediate oxytocin infusion with amniotomy and delayed oxytocin infusion for induction of labour at term.

METHOD: A total of 123 women were randomly chosen to receive either amniotomy and immediate oxytocin infusion (referred to as the 'immediate group') or amniotomy and delayed oxytocin infusion (referred to as the 'delayed group'). The main outcome measure was the proportion of women in established labour at 4 h as well as the proportion that delivered within 12 h of amniotomy. Data were analysed using standard statistical methods.

RESULTS: Women in the immediate group were more likely to be in established labour 4 h post-amniotomy [relative risk (RR) 12.8; 95% CI 55.1-111.7], have a shorter amniotomy to delivery interval (P < 0.001) and achieve vaginal delivery within 12 h (RR 1.5; 95% CI 1.2-12.6). There was no difference between the groups with regards to the mode of delivery, incidence of uterine hyperstimulation and abnormal foetal heart rate recording. Compared to the delayed group, women in the immediate group were more likely to be satisfied with the induction process (RR 4.1, 95% CI 1.1-16.1) and the duration of labour (RR 1.8 95% CI 1.0-3.3).

CONCLUSION: In induction of labour at term, amniotomy and immediate oxytocin infusion is associated with the establishment of active labour at 4 h, a shorter amniotomy-delivery interval and greater maternal satisfaction.