The factors that cause coffee-colored vaginal discharge are: 1. Coffee-colored discharge in the middle of menstruation is probably a symptom of ovulatory bleeding, which is a normal physiological phenomenon. 2. Coffee-colored vaginal discharge in women just after the start of menstruation or around the last day of menstruation is a normal physiological phenomenon due to the low amount of menstrual blood. 3. If a woman has coffee-colored vaginal discharge on a regular basis, she may be suffering from cervicitis or vaginitis, so she needs to cooperate with her doctor for gynecological examination, and then cooperate with her doctor for symptomatic treatment. 4. If a pregnant woman has coffee-colored vaginal discharge during pregnancy, accompanied by pain in the small abdomen, it may be due to preterm miscarriage caused by insufficient secretion of progesterone.