Brown discharge before menstruation may be due to physiological reasons, or it may be related to inflammation, reproductive system tumors and other pathological factors. 1. Physiological reasons: when a woman is menstruating, the increased secretion of estrogen prompts the shedding of the endometrium, while some women in the first menstrual period, due to the body’s low estrogen, the endometrium shed less, stay in the body for too long, resulting in oxidation of the menstrual blood, which will lead to the emergence of brown secretion. 2. Pathological factors: (1) Inflammation: if women suffer from gynecological inflammatory diseases, such as cervicitis, pelvic inflammatory disease, vaginitis, etc., the endometrium and vaginal mucosa become brittle under the stimulation of inflammation, and before the menstruation, due to the congestion of the endometrium, resulting in a small amount of endometrium shedding, the symptom of vaginal bleeding occurs and is mostly accompanied by an increase in vaginal secretions, lower abdominal pain, lumbosacral pain and other symptoms. (2) Tumors of reproductive system: benign tumors such as uterine fibroids and endometrial polyps will lead to brown discharge before menstruation, accompanied by symptoms such as heavy menstrual flow and dribbling menstruation. Malignant tumors such as endometrial cancer, cervical cancer, etc., in addition to the brown discharge before menstruation, there will be foul-smelling discharge, irregular menstruation, lower abdominal pain and other symptoms. There are many causes of brown discharge before menstruation, and you need to go to the hospital for examination to clarify the cause.