In most cases, women have less vaginal bleeding at the beginning of menstruation and at the end of menstruation because the endometrium is less exfoliated, which can be manifested as brown vaginal discharge, but in the middle of menstruation, there is usually more bleeding, which is mostly bright red. It is not normal for a woman to have brown discharge throughout her menstrual period. When this happens, the following possibilities are considered: First, abnormal pregnancy resulting in bleeding, such as pre-eclampsia or ectopic pregnancy. In this case, the poor development or death of the embryo will lead to brown vaginal discharge, accompanied by discomfort in the lower abdomen or lumbago. Secondly, the patient has endocrine disorders that cause low menstrual flow. For example, patients with ovarian hypofunction, premature ovarian failure, hyperprolactinemia, polycystic ovary syndrome, abnormal thyroid function and other diseases can lead to low menstrual flow, which can be clearly diagnosed by checking sex hormone six, anti-mullerian duct antibody and thyroid function. Thirdly, low menstrual flow caused by endometrial damage or adhesions, in this case, low menstrual flow is mostly secondary to abortion and curettage or endometrial inflammation and other surgeries and lesions, which can be clearly diagnosed through hysteroscopy.