Longitudinally and circularly measured EMG activity in the human uterine cervix during labour.

The role of the smooth cervical muscle has not yet been sufficiently explored. For that reason cervical EMG was measured during induced labour of several primiparas and multiparas. Three spiral electrodes were placed on the cervix in order to measure the EMG in the longitudinal and circular direction referred to the cervical axis. A quantitative analysis of changes in the amplitude and frequency of the EMG signals was performed by means of the spectral method. It was found that the EMG measured from the two leads differed in unripe cervices in the latent phase of labour. The differences are illustrated by two cases. Some possible explanations for the different activity are discussed.