Lack of menstruation and low menstrual flow may be caused by pregnancy, excessive weight loss and dieting, intrauterine device, endocrine system diseases, uterine abnormalities and so on. It is recommended to consult a doctor in time to find out the cause and treat it under the doctor’s guidance. 1. Pregnancy: If a woman in her reproductive years does not have menstrual periods, it may be due to miscarriage or ectopic pregnancy, so it is recommended to consult a doctor in time to identify the cause of the problem. 2. Excessive dieting for weight loss: If a woman goes on a diet to lose weight, it may lead to insufficient intake of nutrients in the body, causing endocrine disorders and the phenomenon of irregular and scanty menstruation. 3. Intrauterine device (IUD): A small number of women who have IUDs placed in their uterus may also suffer from low menstrual flow. 4. Endocrine system diseases: when a woman suffers from polycystic ovary syndrome, hyperprolactinemia and other diseases, it is also easy to cause menstrual failure. 5. Abnormalities of the uterus: If a woman suffers from endometrial damage, uterine adhesions, uterine dysplasia and other abnormalities, the endometrial lining of the uterus may be reduced in size, resulting in the phenomenon of irregular and scanty menstruation. Women who do not have menstrual periods should go to the hospital in time to get a clear diagnosis and follow the doctor’s instructions for treatment.