DSP techniques in labor and delivery: digital filters and wavelets

This paper proposes some signal processing techniques to study the forces generated by the uterus during the second stage of the labor. The objective of this study is to find an effective signal analysis method to discriminate: between the forces attributed to the spontaneous contraction versus the maternal expulsive efforts. In addition, it is crucial to decompose the contraction waveform in order to determine the primary frequency band or scale localized forces responsible for the progress in labor. Clinical data has been collected using an 8 bit D/A system with the patient consent and in compliance with the moral and ethical code. Waveforms were collected during the end of first stage and throughout the second stage of labor. Late first stage contraction waveforms were used as the control signal. Wavelet based filtering and a zero phase filtering method using high order low pass Chebychev filter of type II were investigated. Both methods were used to filter out the maternal forces. The results were encouraging in the absence of any better alternative. Better conclusions can be drawn when the outcome of such methods are compared with clinical data related to labor progress