At present, the most widespread method of monitoring uterine contractions activity during pregnancy and labour is the external tocography method. This mechanical method, however, has limited value resulting from its low accuracy and sensibility. Recent progress in new techniques of perinatal monitoring requires a more precise method of monitoring uterine activity. The most promising seems to be electrohysterography, which consists in the recording of electrical uterine activity by means of electrodes attached to abdominal wall. We made an attempt to evaluate the possibility to replace the traditional mechanical method by this electrical one. We developed methods of extraction of the slow wave from an electrohysterogram. This slow wave corresponds to mechanical signal and can be regarded as a contractions wave. Then, using this wave, the contractions detection can be performed in a similar way as in a conventional tocogram. The results obtained allow one to conclude that there is a close relation between the electrical and mechanical signals of uterine activity. It is manifested by a similar number of contractions detected and a large number of contractions being consistent.