[Contractile force, work of the uterus, power developed and resistance of the cervix uteri during labor. Measurements in Poissy units].

Apart from records made of uterine contractions in labour and the progress in dilatation of the cervix, the energy exerted by the uterus to open the cervix can be calculated. The power that is developed and the resistance of the factors that combine to inhibit dilatation of the cervix can also be calculated. Examples are given of promiparous women with a dilatation of 5 cm.