Brown discharge before menstruation is normal if it is caused by partial shedding of the uterine lining, but it is not normal if it is caused by vaginal infection. 1. Partial shedding of uterine lining: Before menstruation, women may experience partial shedding of uterine lining due to the influence of external factors and hormonal imbalance, at this time, there will be a small amount of bleeding as brown secretion, which is generally normal. 2. Vaginal infection: If a woman has vaginal inflammation or vaginal infection, the inflammation will play a certain role in stimulating the endometrium, which will cause abnormal bleeding to a certain extent, such as endometritis, salpingitis, etc., which should be taken seriously in time. If the symptoms of brown discharge are not relieved before the onset of menstruation, or accompanied by other symptoms, you should go to the hospital in a timely manner, to clarify the cause of the targeted treatment.