  Objective: The utility of fetal heart rate (FHR) monitoring can only be
achieved with an acquisition sampling rate that preserves the underlying
physiological information on the millisecond time scale (1000 Hz rather than 4
Hz). For such acquisition, fetal ECG (fECG) is required, rather than the
ultrasound to derive FHR. We tested one recently developed algorithm, SAVER,
and two widely applied algorithms to extract fECG from a single channel
maternal ECG signal recorded over the xyphoid process rather than the routine
abdominal signal. Approach: At 126dG, ECG was attached to near-term ewe and
fetal shoulders, manubrium and xyphoid processes (n=12). FECG served as the
ground-truth to which the fetal ECG signal extracted from the
simultaneously-acquired maternal ECG was compared. All fetuses were in good
health during surgery (pH 7.29+/-0.03, pO2 33.2+/-8.4, pCO2 56.0+/-7.8, O2Sat
78.3+/-7.6, lactate 2.8+/-0.6, BE -0.3+/-2.4). Main result: In all animals,
single lead fECG extraction algorithm could not extract fECG from the maternal
ECG signal over the xyphoid process with the F1 less than 50%. Significance:
The applied fECG extraction algorithms might be unsuitable for the maternal ECG
signal over the xyphoid process, or the latter does not contain strong enough
fECG signal, although the lead is near the mother's abdomen. Fetal sheep model
is widely used to mimic various fetal conditions, yet ECG recordings in a
public data set form are not available to test the predictive ability of fECG
and FHR. We are making this data set openly available to other researchers to
foster non-invasive fECG acquisition in this animal model.
