Rejection of the maternal electrocardiogram in the electrohysterogram signal

The electrohysterogram (EHG) signal is mainly corrupted by the mother´s electrocardiogram (ECG), which remains present despite analog filtering during acquisition, Wavelets are a powerful denoising tool and have already proved their efficiency on the EHG. In this paper, the authors propose a new method that employs the redundant wavelet packet transform. They first study wavelet packet coefficient histograms and propose an algorithm to automatically detect the histogram mode number. Using a new criterion, the authors compute a best basis adapted to the denoising. After EHG wavelet packet coefficient thresholding in the selected basis, the inverse transform is applied. The ECG seems to be very efficiently removed.