What is the most common cause of postpartum hemorrhage?

Uterine atony is recognized as the most common cause of postpartum hemorrhage, accounting for a significant percentage of cases. After the delivery of the placenta, the uterus is expected to contract effectively to reduce blood flow from the placental site and facilitate hemostasis. If the uterus fails to contract—due to factors such as overdistension, prolonged labor, or exhaustion—this condition, known as uterine atony, occurs. As a result, the blood vessels at the site of the placental attachment can remain open, leading to excessive bleeding.

Management typically involves immediate interventions to stimulate uterine contractions, such as administering uterotonics like oxytocin. Understanding uterine atony as the leading cause highlights the importance of monitoring uterine tone in the immediate postpartum period to prevent severe hemorrhage and ensure maternal safety.