Comparison of effect of CTG+STan with CTG alone on emergency Cesarean section rate: STan Australian Randomized controlled Trial (START)

Abstract

OBJECTIVE: To reduce emergency Cesarean section (EmCS) rates by using ST analysis of the fetal electrocardiogram (STan) as an adjunct to continuous cardiotocography (CTG). METHODS: A randomized, controlled trial enrolled patients with a singleton fetus in cephalic presentation, greater than or equal to 36 weeks gestation, requiring continuous electronic fetal monitoring in labor at a tertiary maternity hospital in Adelaide, Australia, between January 2018 and July 2021. Participants were randomized to receive CTG+STan or CTG alone. Calculated sample size was 1818 participants. The primary outcome was EmCS. Secondary outcomes included metabolic acidosis, a composite perinatal outcome, and other maternal and neonatal morbidity and safety outcomes. RESULTS: The present study enrolled 970 women. The primary outcome of EmCS occurred in 107/482 (22.2%) of the CTG+STan arm and in 107/485 (22.1%) in the CTG alone arm (adjusted relative risk (RR), 1.02 (95% CI, 0.81-1.27), P=0.89). CONCLUSIONS: The addition of STan as an adjunct to continuous CTG did not reduce the EmCS rate. The smaller than anticipated sample size for this study meant that it was underpowered to detect absolute differences less than or equal to 5% and therefore this finding is possibly due to a Type 2 error, where a difference may exist but the study was underpowered to detect it.