Late-Breaking Abstract Presentations
Sailesh Kumar, FRCOG, FRCS, MBBS, PhD (he/him/his)
Professor of Obstetrics & Gynaecology
The University of Queensland
Brisbane, Queensland, Australia
Ben W. Mol, MD, PhD (he/him/his)
Professor in Obstetrics & Gynaecology
Monash University
Clayton, Victoria, Australia
William Tarnow-Mordi, MD
Professor
The University of Sydney
Sydney, New South Wales, Australia
Jon Hyett, MBBS, PhD
University of Sydney
Sydney, New South Wales, Australia
Nadia Badawi, PhD
University of Sydney
Sydney, New South Wales, Australia
Annalene Seidler, PhD
Medical Uni Rostock
Rostock, Mecklenburg-Vorpommern, Germany
Helen Liley, MBBS
Mater Research Institute-University of Queensland
Brisbane, Queensland, Australia
Emily Callander, PhD
University Technology Sydney
Sydney, New South Wales, Australia
Vicky Flenady, PhD
Mater Research Institute-University of Queensland
Brisbane, Queensland, Australia
Sue Walker, MBBS MD FRANZCOG CMFM (she/her/hers)
Professor Maternal Fetal Medicine, University of Melbourne
Department of Obstetrics, Gynaecology and Newborn Health, University of Melbourne
Melbourne, Victoria, Australia
Rachel O'Connell, PhD
University of Sydney
Sydney, New South Wales, Australia
Sildenafil citrate (SC) has been proposed as a drug to reduce fetal distress during labour. We assessed its effectiveness in a large placebo controlled clinical trial.
Study Design:
This was a double-blind multicentre randomised controlled trial (Trial Registration Number ACTRN12621000231842) funded by the Australian Medical Research Future Fund. We randomised women attempting vaginal birth at term to 50mg SC every 8 hours during labour (maximum of 3 doses) or placebo. Primary outcome was a composite of 10 adverse neonatal outcomes (intrapartum stillbirth, neonatal death, Apgar score < 4 at 5 minutes, cord artery pH < 7.0, neonatal encephalopathy, neonatal seizures, neonatal respiratory support >4 hours, neonatal unit admission > 48hours, persistent pulmonary hypertension of the newborn and meconium aspiration syndrome). Secondary outcomes were caesarean section (CS) or instrumental vaginal birth (IVB) for fetal distress. The sample size of 3200 women was predicated on a 35% reduction in the RR of the composite perinatal outcome by 35% (7% to 4.55%).
Results:
Between 7 September 2021 and 30 June 2024 we randomized 3257 women (including 18 sets of twins) to SC (1626) and placebo (1631). Induction of labour occurred in 83.5% of the SC cohort and 82.9% of the placebo group. Electronic fetal heart rate monitoring rates were similar (97.4%) in both arms. The primary outcome occurred in 5.1% of women taking SC and 5.2% of those taking placebo [RR 1.02 (0.75-1.37)] with no differences in any of the components of the composite outcome. There was also no difference in rates of CS or IVB for fetal distress [21.1% vs. 18.8%, RR 1.12 (0.98-1.29)]. Blood loss >1000ml occurred in 10.1% in the SC group vs. 7.9% [RR1.29, (1.03-1.60)].
Conclusion:
Maternal oral SC in women undergoing term labour did not result in a reduction of adverse neonatal outcomes potentially related to intrapartum hypoxia.
