Electromyographic activity of the uterus above the placental implantation site

The aim of this study was to evaluate the electromyographic (EMG) activity of the uterus concerning the placental implantation site. In a clinical trial, 55 pregnant women in the last trimester of pregnancy were enrolled. They were divided into two major groups: 25 women had placental implantation site on the anterior and 30 women on the posterior uterine wall. With regard to the presence/nonpresence of contractions, each group was further divided into two subgroups. Uterine EMG activity was recorded by electrodes placed on the abdominal wall. All signals were transferred through a series of amplifiers. Amplified and filtered EMG signals were digitized and written on a hard disk, simultaneously with the signals of external tocodynamometry. From the 30-min EMG recording, we calculated the average root mean square (RMS) and the average median frequency (MF) of the signal. A significant difference of the abdominal EMG activity concerning the placental implantation site was found only in pregnant women with contractions. The RMS was significantly lower in the placental implantation site on the anterior uterine wall, whereas the MF was significantly higher. It can be concluded that the placental implantation site influences the uterine EMG activity registered through the abdominal wall, especially when registered above the placental implantation site.