In primi, the latent phase is often long (about 8 hours) during which effacement occurs; the cervical dilatation averaging only 0.35 cm/hr. In multi, the latent phase is sho (about 4 hours) and effacement and dilatation occur simultaneously. Latent phase is the preparatory phase of the uterus and the cervix before the actual onset of labor. A latent phase that exceeds 20 hours in primigravidae or 14 hours in multiparae is abnormal. The causes include--(1) unripe cervix (2) malposition and malpresentation (3) cephalopelvic dispropoion and (4) premature rupture of the membranes. Management: Expectant management is usually done unless there is any indication (for the fetus or the mother) for expediting the delivery. Rest and analgesic are usually given. When augmentation is decided, medical methods are preferred. Amniotomy is usually avoided. Prolonged latent phase is not an indication for cesarean delivery. Ref : Dutta Obs 9e pg 376.