The coffee-colored discharge from menstruation is caused by low menstrual flow, and there are many reasons for this. 1. First, it may be caused by the presence of uterine cold in women. In addition, some women may be overworked, stay up late or have an irregular diet, resulting in endocrine disorders and this symptom. When women have coffee-colored discharge during menstruation for a long time, they should go to the hospital for an ultrasound examination to clarify the condition of the endometrium and a sex hormone test to find the cause of the problem before treatment.