What is the most common cause of early postpartum hemorrhage?

Uterine atony is recognized as the most common cause of early postpartum hemorrhage, accounting for a significant percentage of cases. This condition occurs when the uterus fails to contract effectively after delivery, resulting in excessive bleeding. Normally, the uterine muscles contract to clamp down on the blood vessels that were attached to the placenta, thus controlling bleeding. In cases of uterine atony, these contractions are inadequate or absent, leading to potential complications. Factors that may contribute to uterine atony include prolonged labor, overdistension of the uterus (such as in cases of multiple gestation or large for gestational age infants), excessive use of anesthesia, and certain medications that may inhibit uterine contractions.

Other causes of early postpartum hemorrhage, while important, do not occur as frequently as uterine atony. For example, retained placenta can lead to hemorrhage by preventing uterine contraction if a portion of the placenta remains in the uterus, but it is not as prevalent as the failure of the uterus to contract initially. Coagulation disorders, while serious, tend to be less common and usually present in patients with known preexisting conditions. Trauma during delivery can also cause bleeding but is not as statistically prevalent as uterine atony in the context of