Low and black menstruation is a symptom of abnormal menstruation, caused by low estrogen levels and endocrine disorders in the following areas: 1. Insufficient ovarian corpus luteum function is the main cause of low estrogen secretion levels. Inadequate thyroid function and abnormal lactogen function can also lead to low and dark menstruation. 2. Post-abortion surgery or endometrial adhesions can also lead to the situation. 3. Long-term malnutrition, weakness or excessive weight loss can lead to low menstrual flow. 4. Changes in the environment, excessive mental tension, psychological stress and exposure to cold can also lead to abnormal menstruation. 5. Qi stagnation and blood stasis caused by poor blood flow , menstrual blood stays in the uterus for a long time and is not easily discharged, and is treated under the specific guidance of a doctor.