The causes of abnormal uterine bleeding may be organic diseases of the uterus, endocrine disorders, and intrauterine residues after delivery or abortion. 1. Organic uterine diseases: when women suffer from endometrial polyps, fibroids, especially submucosal fibroids, it is easy to affect the endometrial shedding and cause abnormal uterine bleeding. 2. Endocrine disorders: abnormalities in ovarian function such as decreased estrogen or insufficient secretion of progesterone may cause endocrine disorders, leading to menstrual disorders and abnormal uterine bleeding. 3. Residuals in the uterine cavity after delivery or abortion: After delivery or abortion, if there are still placenta and fetal membranes in the uterine cavity, it will affect the contraction of the uterus, which will lead to an increase in the amount of vaginal bleeding. Women should pay attention to regular gynecological examination, and if there is abnormal uterine bleeding, they should consult a doctor as soon as possible to find out the cause.