Variability of the ECG waveform in fetal and neonatal lambs

Changes in the waveform of the fetal electrocardiogram (FECG) are being investigated by several groups for its clinical significance with regard to the assessment of fetal condition. During the present authors' experiments with fetal lambs they frequently observed spontaneous FECG waveform changes, also during steady state in control animals. From the examples presented they conclude that the FECG waveform can be very sensitive to changes in the electrode position relative to the fetal heart. Such changes can easily be caused by fetal movements. ECG leads with a minimal sensitivity to these effects should be selected.