Reconstruction of True Fetal Heart Rate Signals Obtained via Ultrasound Bedside Monitor in Relation to Fetal Electrocardiography

Analysis of variability of the fetal heart rate (FHR) signals is very important for fetal well-being assessment. The beat-to-beat variability is described quantitatively by parameters originated from direct fetal electrocardiography, which provides the FHR signal in a form of time event series. Nowadays, monitoring instrumentation is based on the Doppler ultrasound technique. The fetal monitors provide the output signal in a form of evenly spaced measurements. The goal of this work is to present a new method for the FHR signal processing, which enables the extraction of time event series of consecutive heartbeat intervals from the evenly repeated measurements. The proposed correction algorithm enables the recognition and removal of the redundant measurements. Reliable evaluation of the proposed algorithm required the reference time event series, thus the testing FHR signals were obtained from abdominal fetal electrocardiograms.