Vaginal brown discharge 3 days before menstruation belongs to the luteal insufficiency, gynecological organic diseases. The onset of menstruation is the rapid fall in estrogen levels after ovulation, progesterone gradually rises, maintaining a stable peak period, this stable peak period is called the luteal phase about 12 to 14 days, and then fall back to the retreat, when the endometrium is in the secretory phase, by the retreat of progesterone, the endometrium peeled off to form the menstruation. If a small amount of brown vaginal discharge occurs 3 days before menstruation, because in the luteal phase progesterone function is weakened, the ability to retreat the endometrium is insufficient, and the endometrium is peeled off differently, which leads to the phenomenon of brown discharge before menstruation. For patients suffering from cervical polyps, endometrial polyps and other gynecological organic diseases, may also appear 3 days before menstruation brown discharge phenomenon. If there is brown vaginal discharge before menstruation, it is recommended to consult the hospital, under the guidance of the doctor to treat the symptoms, and should not be ignored, so as not to miss the treatment period, affecting the health of the body.