Non-invasive intrapartum fetal ECG: preliminary report

OBJECTIVES: To obtain fetal heart rate, detailed fetal electrocardiography (fECG) signals and uterine contractions during labour using a single device. DESIGN: Prospective observational study. SETTING: Delivery suite at a tertiary referral hospital, London, UK. POPULATION: Fifteen patients at median gestation of 39 weeks (range 24-41) were recruited at median cervical dilatation of 4.0 cm (range 0-10) of whom 8/15 (53%) had intact amniotic membranes. METHODS: Using 12 abdominally sited electrodes, we recorded the composite abdominal signal in pregnancies intrapartum. The recorded data were analysed off-line using a blind signal separation technique. MAIN OUTCOME MEASURES: Success of signal separation and fECG time intervals. RESULTS: Successful fECG signal acquisition was achieved in 12/15 (80%) patients and an averaged fECG waveform acquired. In these patients, P and QRS waves were seen in all cases, and T waves in 11/12 (92%). True beat-to-beat heart rate (HR) was displayed and measures of its variability obtained. The mother's ECG and uterine electrical activity, shown to match tocographically recorded uterine contractions, were also separated and displayed. Failure to acquire fECG in three cases was attributed to excessive abdominal muscular activity and electrical interference. CONCLUSIONS: This study demonstrates a non-invasive technique that displays detailed intrapartum fECG waveforms, HR variability, maternal ECG and uterine contractions simultaneously, all in a single device and which avoids the potential risks of invasive monitoring with a fetal scalp electrode.