Impact of early versus late artificial rupture of membranes during oxytocin induction of labour on the incidence of chorioamnionitis: a randomised controlled trial (ARM trial)

Abstract Background The approach to induction of labour differs internationally, with timing of amniotomy being controversial. Some institutions favour performing artificial rupture of membranes prior to commencement of oxytocin infusion, with the belief that the labour will progress more efficientl...

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Main Authors: Meghan G. Hill, Michelle R. Wise, Emmanuelle Pauleau, Beatrice Treadwell, Lynn Sadler
Format: Article
Language:English
Published: BMC 2025-01-01
Series:Trials
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Online Access:https://doi.org/10.1186/s13063-025-08722-z
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author Meghan G. Hill
Michelle R. Wise
Emmanuelle Pauleau
Beatrice Treadwell
Lynn Sadler
author_facet Meghan G. Hill
Michelle R. Wise
Emmanuelle Pauleau
Beatrice Treadwell
Lynn Sadler
author_sort Meghan G. Hill
collection DOAJ
description Abstract Background The approach to induction of labour differs internationally, with timing of amniotomy being controversial. Some institutions favour performing artificial rupture of membranes prior to commencement of oxytocin infusion, with the belief that the labour will progress more efficiently. In other institutions, the approach recommended is for oxytocin infusion with intact amniotic membranes until the person has reached the active phase of labour, citing risk of infection with early amniotomy. Current evidence is inconclusive. We are performing a randomised controlled trial assessing whether delaying amniotomy until the active phase of labour can decrease the rate of chorioamnionitis. Methods This is a randomised controlled trial at a single centre in New Zealand. Pregnant people undergoing induction of labour at ≥ 37 weeks gestational age with intact membranes and a singleton gestation are eligible for the trial. Participants are randomised to ‘Early’ amniotomy, at the commencement of oxytocin infusion, or to ‘Late’ amniotomy, when they have reached a cervical dilation of 6 or more centimetres or when they have been receiving oxytocin infusion for 12 h. The primary outcome of the trial is chorioamnionitis. To detect a decrease in chorioamnionitis from 9 to 3% with a power of 80% and a 95% CI, we will require 488 participants in total, randomised in a 1:1 ratio. Discussion If delaying amniotomy reduces the rate of chorioamnionitis, this is important to inform future practice. Chorioamnionitis entails risk to both the pregnant person and the fetus and is an important contributor to neonatal sepsis, neonatal intensive care unit admission, maternal sepsis, caesarean, wound infection and postoperative infective complications. Conversely, if the rate of chorioamnionitis is not affected by timing of amniotomy, this will allow for safe individualization of care. Trial registration The trial is registered on the Australian and New Zealand Clinical Trials Registry, anzctr.org.au. Full registry title is ‘Impact of early versus late artificial rupture of membranes during oxytocin induction of labour on the incidence of chorioamnionitis: A randomised controlled trial’. Trial ID: ACTRN12621000405819. Date registered 14 April 2021.
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spelling doaj-art-e328bcbe1aa04cac9d89ebdcfa6697ad2025-01-26T12:51:07ZengBMCTrials1745-62152025-01-0126111010.1186/s13063-025-08722-zImpact of early versus late artificial rupture of membranes during oxytocin induction of labour on the incidence of chorioamnionitis: a randomised controlled trial (ARM trial)Meghan G. Hill0Michelle R. Wise1Emmanuelle Pauleau2Beatrice Treadwell3Lynn Sadler4Department of Obstetrics and Gynaecology, The University of AucklandDepartment of Obstetrics and Gynaecology, The University of AucklandWomen’s Health, Te Whatu Ora Te Toka Tumai AucklandWomen’s Health, Te Whatu Ora Te Toka Tumai AucklandWomen’s Health, Te Whatu Ora Te Toka Tumai AucklandAbstract Background The approach to induction of labour differs internationally, with timing of amniotomy being controversial. Some institutions favour performing artificial rupture of membranes prior to commencement of oxytocin infusion, with the belief that the labour will progress more efficiently. In other institutions, the approach recommended is for oxytocin infusion with intact amniotic membranes until the person has reached the active phase of labour, citing risk of infection with early amniotomy. Current evidence is inconclusive. We are performing a randomised controlled trial assessing whether delaying amniotomy until the active phase of labour can decrease the rate of chorioamnionitis. Methods This is a randomised controlled trial at a single centre in New Zealand. Pregnant people undergoing induction of labour at ≥ 37 weeks gestational age with intact membranes and a singleton gestation are eligible for the trial. Participants are randomised to ‘Early’ amniotomy, at the commencement of oxytocin infusion, or to ‘Late’ amniotomy, when they have reached a cervical dilation of 6 or more centimetres or when they have been receiving oxytocin infusion for 12 h. The primary outcome of the trial is chorioamnionitis. To detect a decrease in chorioamnionitis from 9 to 3% with a power of 80% and a 95% CI, we will require 488 participants in total, randomised in a 1:1 ratio. Discussion If delaying amniotomy reduces the rate of chorioamnionitis, this is important to inform future practice. Chorioamnionitis entails risk to both the pregnant person and the fetus and is an important contributor to neonatal sepsis, neonatal intensive care unit admission, maternal sepsis, caesarean, wound infection and postoperative infective complications. Conversely, if the rate of chorioamnionitis is not affected by timing of amniotomy, this will allow for safe individualization of care. Trial registration The trial is registered on the Australian and New Zealand Clinical Trials Registry, anzctr.org.au. Full registry title is ‘Impact of early versus late artificial rupture of membranes during oxytocin induction of labour on the incidence of chorioamnionitis: A randomised controlled trial’. Trial ID: ACTRN12621000405819. Date registered 14 April 2021.https://doi.org/10.1186/s13063-025-08722-zArtificial rupture of membranesAmniotomyChorioamnionitisOxytocinLabour induction
spellingShingle Meghan G. Hill
Michelle R. Wise
Emmanuelle Pauleau
Beatrice Treadwell
Lynn Sadler
Impact of early versus late artificial rupture of membranes during oxytocin induction of labour on the incidence of chorioamnionitis: a randomised controlled trial (ARM trial)
Trials
Artificial rupture of membranes
Amniotomy
Chorioamnionitis
Oxytocin
Labour induction
title Impact of early versus late artificial rupture of membranes during oxytocin induction of labour on the incidence of chorioamnionitis: a randomised controlled trial (ARM trial)
title_full Impact of early versus late artificial rupture of membranes during oxytocin induction of labour on the incidence of chorioamnionitis: a randomised controlled trial (ARM trial)
title_fullStr Impact of early versus late artificial rupture of membranes during oxytocin induction of labour on the incidence of chorioamnionitis: a randomised controlled trial (ARM trial)
title_full_unstemmed Impact of early versus late artificial rupture of membranes during oxytocin induction of labour on the incidence of chorioamnionitis: a randomised controlled trial (ARM trial)
title_short Impact of early versus late artificial rupture of membranes during oxytocin induction of labour on the incidence of chorioamnionitis: a randomised controlled trial (ARM trial)
title_sort impact of early versus late artificial rupture of membranes during oxytocin induction of labour on the incidence of chorioamnionitis a randomised controlled trial arm trial
topic Artificial rupture of membranes
Amniotomy
Chorioamnionitis
Oxytocin
Labour induction
url https://doi.org/10.1186/s13063-025-08722-z
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