Which condition is associated with an increased risk of postpartum hemorrhage?

Retained placental fragments is associated with an increased risk of postpartum hemorrhage due to their potential to prevent the uterus from contracting effectively after delivery. When the placenta is not fully expelled from the uterus, it can lead to prolonged uterine atony, which is one of the primary causes of postpartum hemorrhage. The presence of these fragments interferes with normal uterine involution and can lead to significant blood loss.

In contrast, while factors like multiparity and cervical laceration can contribute to the overall risk of complications during and after delivery, they are not as directly linked to postpartum hemorrhage as retained placental fragments are. Multiparity may be associated with increased chances of uterine atony but is not a direct cause, and cervical lacerations typically cause localized bleeding, which can often be managed effectively if identified and treated promptly. Placenta previa also poses serious risks during pregnancy and delivery, including bleeding, but it is primarily a risk factor leading to hemorrhage during the antepartum and intrapartum periods rather than postpartum. Thus, retained placental fragments are specifically linked to the mechanisms of postpartum hemorrhage.