The causes of vaginal bleeding include pregnancy causes and non-pregnancy causes. 1. Pregnancy causes: including miscarriage, ectopic pregnancy, placental abruption and so on. (1) Miscarriage: Clinical manifestations include menopause, abdominal pain and vaginal bleeding. It occurs when the pregnancy has not reached 28 weeks and the fetus weighs less than 1000g and is terminated. (2) Ectopic pregnancy: clinical manifestations are menopause, abdominal pain and vaginal bleeding. The more common ectopic pregnancy is tubal ectopic pregnancy. (3) Placental abruption: clinical manifestations include vaginal bleeding, abdominal pain, which may be accompanied by increased uterine tension and uterine pressure. 2. Non-pregnancy causes: including inflammation of the reproductive system and tumors of the reproductive system. (1) Inflammation of the reproductive system: inflammation stimulates the mucous membrane to break down, and vaginal bleeding may appear. (2) Tumors of reproductive system: for example, cervical cancer manifests as contact vaginal bleeding; uterine fibroid manifests as increased menstrual flow and prolonged menstrual period. There are many reasons for vaginal bleeding, and it is recommended to consult a doctor in time to clarify the cause of the disease and then target treatment.