Very small and brown menstrual flow may be caused by ovulation bleeding, preeclampsia, ectopic pregnancy and other reasons. 1. Ovulation bleeding: During ovulation, a short drop in the level of estrogen in the body can cause a small amount of shedding of the endometrium, resulting in a small amount of bleeding, but due to the small amount of bleeding, it is not discharged in time, and the blood oxidizes to brown secretion in the vagina. 2. Pre-eclampsia: In early pregnancy, due to pre-eclampsia, a small amount of vaginal bleeding can occur, starting with brown discharge, and then the amount can gradually increase and cause abdominal pain. 3. Ectopic pregnancy: generally have a history of menopause, can also be seen in the vagina brown discharge, or vaginal bleeding performance. Menstruation is very small and brown there may be other reasons, it is recommended to consult a doctor in a timely manner, improve the relevant examination, under the guidance of a professional doctor to clarify the cause of the disease, targeted treatment.