Causes of uterine bleeding include both pregnancy-related uterine bleeding and non-pregnancy-related uterine bleeding. 1. Pregnancy-related uterine bleeding: including miscarriage, placenta praevia, placenta previa, and postpartum hemorrhage. (1) Miscarriage: manifested by abdominal pain and vaginal bleeding after menopause. (2) Placenta praevia: manifested as repeated vaginal bleeding without cause and painless, commonly in late pregnancy. (3) Placental abruption: manifested by vaginal bleeding, abdominal pain, which may be accompanied by increased uterine tone and uterine pressure. (4) Postpartum hemorrhage: refers to bleeding ≥500ml within 24h of delivery, and the common causes include weak uterine contraction, soft birth canal laceration, and placental factors. 2. Non-pregnancy-related uterine bleeding: common in inflammatory diseases and gynecological tumors. (1) Inflammatory diseases: including vaginitis, cervicitis, endometritis, etc., manifested by abundant vaginal discharge, which may present symptoms such as indirect bleeding and bleeding after sexual intercourse. (2) Gynecological tumors: cervical cancer manifests as contact vaginal bleeding, endometrial cancer manifests as postmenopausal vaginal bleeding. If abnormal uterine bleeding is found, one should go to the hospital in time and follow the doctor’s advice for treatment.