If there is coffee-colored discharge before menstruation, it may be due to the following reasons: 1. It is likely to be caused by progesterone deficiency, which will lead to irregular shedding of the uterine lining and cause coffee-colored discharge before menstruation. 2. You can do sex hormone six tests to understand the endocrine situation, if necessary, in the second half of menstruation can be supplemented with progesterone, will improve this symptom. 2, may be caused by pregnancy, may be ectopic pregnancy, may be biochemical pregnancy, may be pre-menstrual miscarriage. It is recommended to do further examination, you can draw blood to find out whether the blood HCG appears to be elevated, if elevated, need to do further examination to find out whether it is intrauterine pregnancy, miscarriage with aura, ectopic pregnancy or biochemical pregnancy.