Objective: To investigate whether use of ST analysis of the fetal electrocardiogram (STan) as an adjunct to continuous cardiotocography (CTG) reduces the rate of emergency Cesarean section (EmCS) compared with CTG alone.Methods: This was a randomized controlled trial of patients with a singleton fetus in cephalic presentation at >= 36 weeks' gestation, requiring continuous electronic fetal monitoring during labor at a tertiary maternity hospital in Adelaide, Australia, between January 2018 and July 2021. Participants were randomized to undergo CTG + STan or CTG alone. The calculated sample size was 1818 participants. The primary outcome was EmCS. Secondary outcomes included metabolic acidosis, a composite adverse perinatal outcome, and other maternal and neonatal morbidity and safety outcomes.Results: The present study enrolled 970 women, of whom 967 were included in the primary analysis. EmCS occurred in 107/482 (22.2%) deliveries in the CTG + STan arm and in 107/485 (22.1%) in the CTG arm (adjusted relative risk, 1.02 (95% CI, 0.81-1.27); P = 0.89). There was no difference in the rate of adverse maternal or neonatal outcomes between arms.Conclusions: The addition of STan as an adjunct to continuous CTG did not reduce the EmCS rate. The smaller-than-anticipated sample size meant that this study was underpowered to detect absolute differences of <= 5% and, therefore, this negative finding could be due to a Type-2 error. (c) 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Cardiotocography is almost ubiquitous in its use in intrapartum care. Although it has been demonstrated that there is some benefit from continuous intrapartum fetal monitoring using cardiotocography, there is also an increased risk of caesarean section which is accompanied by short-term and long-term risks to the mother and child. There is considerable potential to reduce unnecessary operative delivery with up to a 60% false positive diagnosis of fetal distress using cardiotocography alone. ST analysis of the fetal electrocardiogram is a promising adjunct to cardiotocography alone, and permits detection of metabolic acidosis of the fetus, potentially reducing false positive diagnosis of fetal distress. This study will be a single-centre, parallel-group, randomised controlled trial, conducted over 3 years. The primary hypothesis will be that the proportion of women with an emergency caesarean section on ST analysis will not equal that for women on cardiotocography monitoring alone. Participants will be recruited at the Women’s and Children’s Hospital, a high-risk specialty facility with approximately 5000 deliveries per annum. A total of 1818 women will be randomised to the treatment or conventional arm with an allocation ratio of 1:1, stratified by parity. The primary outcome is emergency caesarean section (yes/no). Statistical analysis will follow standard methods for randomised trials and will be performed on an intention-to-treat basis. Secondary maternal and neonatal outcomes will also be analysed. Additional study outcomes include psychosocial outcomes, patient preferences and cost-effectiveness. Approximately 20% of Australian babies are delivered by emergency caesarean section. This will be the first Australian trial to examine ST analysis of the fetal electrocardiogram as an adjunct to cardiotocography as a potential method for reducing this proportion. The trial will be among the first to comprehensively examine ST analysis, taking into account the impact on psychosocial well-being as well as cost-effectiveness. This research will provide Australian evidence for clinical practice and guideline development as well as for policy-makers and consumers to make informed, evidence-based choices about care in labour. ANZCTR, ACTRN1261800006268 . Registered on 19 January 2018.