Extremely low and almost no menstrual flow may be related to pregnancy, or it may be caused by endocrine disorders, ovarian function decline and other reasons. 1. Pregnancy: By the time of menstruation if the menstrual flow is extremely low and almost nonexistent, you should be alert to the possibility of pregnancy. If you usually have sex and do not take any contraceptive measures, you may be pregnant, and you may have a small amount of bleeding due to miscarriage with precursor or ectopic pregnancy. 2. Endocrine disorders: usually caused by abnormal thyroid function, hyperprolactinemia, polycystic ovary syndrome and other factors, due to endocrine disorders, affecting the hormone level, it may show a very small amount of menstruation almost no situation. 3. Decline in ovarian function: There are many reasons for the decline in ovarian function, such as age, ovarian surgery, autoimmune diseases, chemotherapy and radiotherapy, etc., all of which may cause women’s ovarian function to decline, which may show a very small amount of menstruation almost none. In addition, there may be other reasons for this situation, if accompanied by obvious discomfort symptoms, it is recommended to seek medical advice as soon as possible, through the improvement of the relevant examination, to confirm the diagnosis of the causal factors, and then follow the doctor’s instructions for targeted treatment.