Abstract: The invention relates to the use of a pulse oximetry sensor device. Based on standard methods for recording material labor activity during birth, reliable signals may be created so that a midwife obtains measuring values indicating clear information of maternal labor activity. The invention suggests the use of a pulse oximetry sensor device which measures the change in the oxygen content in the fetal blood during birth. The pulse oximetry sensor device is provided with a least one light emitter and at least one receiver, connected with an analyzing device, and attached to the leading part of the fetus for recording the maternal labor activity.