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Notes: Objectives To document the duration of fetal cardiac time intervals in uncomplicated singleton pregnancies using a novel non-invasive fetal electrocardiography (fECG) system and to demonstrate this technique's ability to acquire recordings in twin and triplet pregnancies.Design Prospective cross sectional observational study.Setting Antenatal wards and clinics, day assessment unit and centre for fetal care at a tertiary referral hospital, London, UK.Population or Sample Three hundred and four singleton and multiple pregnancies, 15–41 weeks of gestation.Methods Using electrodes sited on the maternal abdomen, a fetal electrocardiography (fECG) system was developed and tested on 304 pregnant women from 15 to 41 weeks of gestation, of whom 241 were uncomplicated singletons, 58 had twin and 5 had triplet pregnancies. The composite abdominal signals were stored on a laptop computer and the fECG derived off-line using a digital signal processing technique. For singletons, linear regression was used to analyse PR, QRS, QT and QTc intervals, and construct time-specific reference ranges.Main outcome measure Duration of fECG time intervals as a function of gestational age. Success of signal seperation in singleton, twin and triplet pregnancies.Results For singletons, a total of 250 recordings was obtained from 241 individuals with a signal separation success rate of 85% (213/250). Success rates were significantly poorer between 27 and 36 weeks of gestation (2 × k χ2, P 〈 0.0001), with 84% (31/37) of separation failures occurring during this period. P, Q, R and S waves were seen in all cases where fetal signals were separated and were used to generate fECG time interval reference ranges. In 22% (43/199) of analysed cases, no T waves were identified, 63% (27/43) of whom were ≤24 weeks of gestation. In twins and triplets, separate fetal signals were obtained in 78% (91/116) and 93% (14/15), respectively; P, Q, R and S waves were evident in all averaged fECGs, while T waves were identified in 59% (54/91) and 57% (8/14).Conclusions This study provides reference ranges with gestation for fECG intervals derived non-invasively from normal singleton pregnancies and demonstrates the feasibility of obtaining complete fECG recordings non-invasively across a wide gestational range in pregnancies of all pluralities. The fECG time intervals described will enable the identification of pathological fECG recordings from high risk pregnancies where fECG abnormalities are suspected.

Notes: 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.