Electrohysterographic analysis of uterine contraction propagation with labor progression: a preliminary study

Monitoring the uterine contractions provides important prognostic information during pregnancy and delivery. In particular, the propagation of uterine activity is closely related to the contraction efficiency. In the present study, a propagation analysis of uterine contraction is carried out by simultaneously recording the electrohysterogram (EHG) and the internal uterine pressure (IUP) on one woman in the last 4 hours of labor. The EHG, recorded in a monopolar multi-electrode configuration, was first processed in each channel in order to provide an accurate estimate of the IUP. The IUP estimate resulted in a correlation coefficient with the simultaneously recorded IUP r=0.74. Eventually, in order to evaluate the propagation of the muscular electrical activity, the delays among the IUP estimates in each channels were calculated by cross correlation function maximization. In agreement with previous studies, no preferred direction of propagation was singled out and pacemaker areas changed from contraction to contraction. However, by analyzing the occurrences of each pacemaker area, the uterine upper part resulted the most frequent location. Moreover, the close agreement between the number of simultaneously active electrodes and the IUP peak values (r=0.76) revealed a relationship between the spreading of action potentials and the maximum amplitude of contraction.