Aunt refers to menstrual blood. There are many reasons that cause women to have brown menstrual blood during physiological period, mainly including normal physiological phenomenon, endocrine disorders, and endometrial damage. It is recommended to consult a doctor in time to find out the cause and treat it under the doctor’s guidance. 1. Normal physiological phenomenon: if the patient’s menstrual blood becomes brown only in the last two days of physiological period, and the menstrual blood is normal dark red color before that, it means that the woman’s menstruation is about to end, which is a normal physiological phenomenon. 2. Endocrine disorders: If women have brown menstrual blood throughout the physiological period, it may suggest that the patient’s estrogen level is too low, and the endometrial hyperplasia is incomplete, leading to a decrease in the patient’s bleeding and thus the symptoms of brown menstrual blood. 3. Endometrial damage: due to abortion surgery or other uterine surgery, resulting in endometrial damage or uterine adhesions, thus reducing the amount of endometrial stripping, which leads to a decrease in the amount of menstrual flow, the color of menstrual blood becomes brown. There may also be other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment.