Graphic representation of disorders of the functional divisions of labor, with cervical dilation or fetal station as ordinate and time as abscissa. At the top, the normal dilation curve is compared with the preparatory division abnormality of prolonged latent phase (1). The middle group presents the protraction disorders of the dilational division—protracted active-phase dilation (2) and protracted descent (3). At the bottom are the pathologic states of the pelvic division, including prolonged deceleration phase (4), secondary arrest of dilation (5), arrest of descent (6), and failure of descent (7). The broken portions of the curves represent mean normal patterns; the unbroken portions represent abnormal patterns.