PPH is the most common cause of maternal death worldwide and most cases occur within the first 24 hours after delivery. PPH occurring between 24 hours and 12 weeks after delivery is defined as secondary PPH. PPH is generally caused by the failure of the uterus to contract adequately; genital tract trauma (i.e. vaginal or cervical lacerations); uterine rupture; retained placental tissue; or maternal bleeding disorders.
The active management of the third stage of labour by skilled birth attendants is recommended to reduce the incidence of PPH; this includes the administration of a uterotonic after the birth; clamping of the cord after uterine contraction and controlled delivery of the placenta and uterine massage. (whqlibdoc.who.int/publications/2009/9789241598514_eng.pdf)