An accurate measure of instantaneous fetal heart rate (FHR) and FHR beat-to-beat variability (BTBV), is an important prognostic indicator of fetal well being [10]. Present techniques used to noninvasively measure FHR, ie, Doppier ultrasound (US), are not capable of providing accurate FHR beat-to-beat variability [6].

The purpose of this paper is two fold. First, we report an evaluation of the accuracy of a new noninvasive abdominal fetal ECG (AFECG) mode of FHR monitoring, which utilizes Adaptive Digital Filtering (ADF). The evaluation compares the beat-to-beat fetal ECG RR interval measurements, obtained from maternal abdominal ECG electrodes, with those RR intervals simultaneously obtained from a direct fetal scalp electrode (FSE). Second, we provide a comparison of our evaluation of this noninvasive abdominal fetal ECG FHR monitoring technique with prior evaluations of Doppler US FHR monitoring techniques currently in use.