Uterine atony can lead to postpartum hemorrhage, and it is the most common cause of such bleeding. After the delivery of the baby, the contraction and retraction of uterine muscle fibers rapidly reduce the size of the placental separation site. Simultaneously, the surrounding spiral arteries undergo physiological ligation, and the blood sinuses close, effectively controlling the bleeding. Therefore, any factor that affects the contraction and retraction function of the uterine muscles can cause hemorrhage due to uterine atony. Common causes include systemic factors such as excessive maternal anxiety, fear of childbirth, physical weakness, or chronic systemic diseases. Obstetric factors include prolonged labor leading to excessive physical exhaustion, placenta previa, placental abruption, hypertensive disorders of pregnancy, and intrauterine infections, which can cause uterine muscle edema or bleeding that impairs contraction. Uterine factors encompass overstretching of uterine muscle fibers, damage to the uterine wall, and uterine pathologies. Pharmacological factors primarily involve the excessive use of sedatives, anesthetics, or uterine relaxants during labor.