Computerised analysis of the fetal heart rate and relation to acidaemia at delivery

OBJECTIVE: To identify the individual features of the computerised analysis of the cardiotocograph that relate to arterial pH and base deficit at delivery. DESIGN: Retrospective observational study. SETTING: Teaching hospital labour wards. PARTICIPANTS: 679 women requiring continuous intrapartum fetal monitoring. METHODS: Fetal heart and uterine contraction data were obtained using the Nottingham Fetal ECG monitor. Fetal heart rate patterns for the last half-hour preceding delivery were analysed using a computer algorithm developed for intrapartum application. The significance of the areas under receiver operator characteristic curves were calculated. MAIN OUTCOME MEASURES: Umbilical arterial pH and base deficit at delivery. RESULTS: Three parameters, fetal bradycardia, total deceleration area and the deceleration area after a contraction had receiver operator characteristic curves that significantly predict a low umbilical arterial pH and base deficit at delivery (areas under receiver-operator characteristic curves = 0.53, SD 0.01 P = 0.03; 0.60, SD 0.03 P = 0.002; 0.62 SD 0.04 P < 0.001, respectively). Tachycardia, accelerations and variability did not. CONCLUSIONS: The individual components of the computerised analysis of the fetal heart rate that predict acidaemia at delivery are identified.