Application of wavelet transform to uterine electromyographic signals recorded using abdominal surface electrodes

Objective: The aim of this study was to explore the use of the wavelet transform technique to extract and display simultaneously the time, frequency and amplitude information corresponding to electromyographic (EMG) activity of the uterus during labor recorded using abdominal electrodes. Methods: Uterine EMG signals were recorded from patients in labor using three pairs of electrodes placed across the maternal abdomen. In all the patients uterine activity was also recorded either from an intrauterine pressure catheter (IUPC) or a tocodynamometer. The EMG signals were analyzed using spectral analysis and wavelet analysis. Results: Uterine EMG bursts corresponded with uterine activity measured with either the IUPC or the tocodynamometer. Using wavelet analysis a time-frequency-amplitude plot was obtained to separate out the frequency components relating to uterine EMG activity. Conclusion: This study showed that the wavelet transform could be a useful tool to study the uterine EMG activity. Continued studies on frequency content, amplitude and origin of uterine EMG activity could be helpful in understanding uterine contraction.