If a 40-year-old woman has a low menstrual flow, she should consider ovarian function decline, thyroid function abnormalities, endometrial damage or adhesions, and the patient should determine the cause and treat the cause. 1. Ovarian function decline: 40 years old is in the transition period of menopause, with the decline of ovarian function, estrogen and progesterone levels decline, which can be manifested as a gradual shortening of the menstrual cycle, reduced menstrual flow, accompanied by anxiety, uncontrolled emotions, concentration, sleep disorders, etc. This may be accompanied by anxiety, uncontrolled mood, lack of concentration, sleep disorders, etc. Menopause is a normal and natural phenomenon. Patients should exercise regularly in daily life, eat a balanced diet, stop smoking and limit alcohol, keep a happy spirit, and pay attention to the prevention of osteoporosis and avoid fractures. 2. Abnormal thyroid function: When suffering from lower thyroid hormone, it will affect the metabolism and lead to endocrine disorders in the body, and women may experience menstrual disorders, such as low menstrual flow and other symptoms. Patients should have exogenous thyroid hormone supplementation under the guidance of a doctor to maintain thyroid function in the normal range and alleviate the symptoms of low menstrual flow; 3, endometrial damage, adhesions: patients who have done abortion or scraping and other uterine operations may cause endometrial damage or adhesions, patients should promptly go to the hospital to do hysteroscopy for examination and follow medical advice for treatment, if the endometrial damage is caused by the endometrium. If the damage is caused by endometrial damage, endometrial repair drugs such as estradiol valerate tablets and progesterone can be used for treatment.