SEPARATION OF FETAL AND MATERNAL ECG COMPLEXES FROM A MIXED-SIGNAL USING AN ALGORITHM-BASED ON LINEAR-REGRESSION

Fetal scalp ECG and Doppler ultrasound are the two methods universally used to derive the fetal heart rate (FHR) for cardiolocography. Other fetal signal sources have not been used successfully because of the c omplexity of the signal and the need for an additional maternal ECG in put. In this paper, we present an algorithm for separating the fetal a nd maternal ECG signals obtained from intrauterine electrodes during l abour The algorithm detects all occurrences of ECC complexes and uses linear regression functions to compare each complex with a set templat es. Sets of templates are identified as either maternal or fetal in or igin and two signals are output for heart rate measurement. The output s are also processed to eliminate artefacts that may occur when the ma ternal and fetal complexes are coincident. The algorithm processes 10 seconds of data at a time (in about 200 ms on a standard PC) while a f urther 10 s of data is being acquired. It has the advantage that no ex tra input is required, such as maternal ECG obtained from chest leads, and only assumes that two different populations of complexes of two d ifferent shapes are present in the input signal. The algorithm could a lso be used for the separation of fetal and maternal signals obtained from abdominal electrodes.