Abdominal-Lead Fetal Electrocardiographic R-Wave Enhancement for Heart Rate Determination

The reliability of fetal heart rate (FHR) from external abdominal-lead electrocardiographic waveforms depends upon the R-wave detection capability of the monitoring device. Assuming that the maternal component of the ECG is canceiled by techniques described elsewhere [1]-[4], we are left with a fetal electrocardiogm (FECG) which may be conrupted by high noise levels. This paper describes several digital signal processing techniques by which the detection of fetal R-waves is improved. These techniques-narrow band-pass filtering, local peak differencing, autoregressive filtering, and matched filtering-are theoretically developed. The performance of each technique is measured and analyzed for two sample fetal ECG inputs.