The large amount of blood during a woman’s menstrual period may be related to endocrine disorders, uterine space-occupying lesions, intrauterine devices and other factors. 1. Endocrine disorders: if the female hormone secretion is abnormal and estrogen secretion is increased, it will easily lead to excessive proliferation of the endometrium, and the shedding of the endometrium during menstruation will be manifested as an increase in menstrual flow. 2. Uterine space-occupying lesions: including uterine fibroids, uterine fibroadenomas, endometrial polyps, etc., because the diseased tissues have an effect on the morphology of the uterine cavity, resulting in increased shedding of the endometrium and increased menstrual flow. 3. Intrauterine device (IUD): IUD affects the contraction of the uterus, which keeps the blood vessels in the uterus open, resulting in increased bleeding. In addition, IUD increases fibrinolytic enzymes in the uterus, which affects blood coagulation and leads to increased menstrual flow. It is recommended that women with heavy menstrual flow should consult a doctor in time to have the cause clarified by relevant examinations, and be treated under the doctor’s guidance.