Hello there...., brown discharge per vagina before menstruation has many reasons... Both Physiological and pathological causes will result in brown discharge.... Some of the causes include hormonal imbalances, stress, or due to delay in normal periods....sometimes infection such as pelvic inflammatory disease, chlamydia and gonorrhea also presents as brown discharge per vagina.....Kindly consult your Gynecologist and undergo per vaginal examination to know the underlying cause...