What is the most common cause of postpartum hemorrhage?

Uterine atony is identified as the most common cause of postpartum hemorrhage due to its direct relationship with uterine contractions following delivery. After the placenta is expelled, it is crucial for the uterus to contract effectively to compress blood vessels in the area where the placenta was attached. When uterine atony occurs, the uterus fails to contract adequately, leading to increased blood loss. This is particularly important because the immediate postpartum period involves significant physiological changes, and any failure in uterine tone can rapidly result in significant hemorrhage.

Retention of placental tissue can contribute to bleeding but is less frequent compared to the prevalence of uterine atony. Coagulation disorders and infections, while serious complications, are also less common causes of postpartum hemorrhage compared to atony. The focus on ensuring proper uterine contraction and recognizing signs of atony is critical in postpartum care, as timely interventions can effectively manage and reduce the risk of severe hemorrhage.