The impact on obstetric and perinatal outcomes in term infants following the introduction of a colour‐coded, hierarchical cardiotocography classification system: A retrospective non‐inferiority study.

Background: Queensland introduced a colour‐coded cardiotocograph (CTG) classification system (green, blue, yellow and red) to complement the Royal Australian and New Zealand College of Obstetricians and Gynaecologists prose‐based classification system of 'low, unlikely, maybe or likely' fetal compromise. Aims: The aim of the study was to determine the clinical impact of the introduction of the colour‐coded CTG classification system compared to the prose‐based system. We hypothesised there would be no change in the rate of operative delivery for intrapartum fetal compromise (OD‐IFC). Materials and methods: This retrospective non‐inferiority study from November 2014 to May 2018 used routinely collected data from the Mater Mother's Hospital. Non‐insured women with a singleton, non‐anomalous, cephalic fetus at term, attempting a vaginal birth with continuous intrapartum CTG were included. The primary outcome was OD‐IFC. Secondary outcomes included various obstetric and perinatal outcomes. Non‐inferiority analysis was performed with a pre‐specified non‐inferiority margin of 2% risk difference. Results: Eleven thousand seven hundred and twenty‐seven participants were included. The OD‐IFC rate was similar across the study groups (prose‐based 15.1% vs colour‐coded 15.3%, adjusted odds ratio (aOR) 1.02, 95% CI 0.93–1.13) with the adjusted risk difference of 0.29% (95% CI −0.98 to 1.56), which did not exceed the inferiority margin. There were more spontaneous (aOR 1.11, 95% CI 1.04–1.19) and fewer instrumental (aOR 0.87, 95% CI 0.80–0.95) vaginal births in the colour‐coded cohort. There were no differences in neonatal outcomes. Conclusions: Reassuringly, the colour‐coded CTG classification system was non‐inferior to the prose‐based system, did not influence OD‐IFC but was associated with more spontaneous vaginal deliveries. [ABSTRACT FROM AUTHOR]