A method of monitoring the progress of labor in a mother during childbirth, by using a position sensor to measure a predetermined point on the mother; monitoring the location of the position sensor in three-dimensional space; and monitoring the location of the fetal presenting part with respect to the predetermined point on the mother. The location of the fetal presenting part may be indicated by a similar position sensor, or by imaging. Other conditions, such as effacement, cervical dilatation, and cervical position may also be monitored in a similar manner. A reference or affixation point may be provided to the position sensor by, for example, attaching a key or shaped object to one or more points on the fetus or mother.