The graphic analysis of labor

Abstract 1. The efficacy of plotting cervical dilatation against time as a method of graphically analyzing labor is demonstrated. 2. The sigmoid characteristics of the curves thus obtained in primiparas at term are illustrated. 3. The first stage of labor is divided into four phases based on the graphic alterations noted. Their respective limits are defined. 4. Primary and secondary inertia are redefined in terms of deviation from the “normal.” 5. The application of this method to the study of the effects of sedation, stimulation, anesthesia, etc., upon the course of labor is indicated. 6. The value of this method for the study of individual labors, in progress, is stressed.