There are many reasons why women do not have menstruation for a month, mainly including pregnancy, disease, medication, environmental factors and so on. It is recommended to consult a doctor in time to find out the cause, and under the guidance of the doctor to observe or medication. 1. Pregnancy: It is recommended that the patient go to the hospital for a blood HCG (human chorionic gonadotropin) test to initially determine whether she is pregnant. If pregnancy is confirmed, patients are advised to take more folic acid-rich foods during early pregnancy, pay attention to rest, avoid overwork and undergo regular checkups. 2. Disease factors: premature ovarian failure, polycystic ovary syndrome, hyperprolactinemia and other diseases can affect the hypothalamus-pituitary-ovarian axis of neuroendocrine regulation, which can also lead to delayed menstruation. 3. Drug factors: If the patient’s menstrual period is delayed due to previous oral contraceptive drugs such as levonorgestrel tablets, it is recommended that the patient exclude pregnancy and then observe the treatment. 4. Environmental factors: A sudden change in the patient’s living or working environment, or catching a cold, etc., may cause menstrual disorders, resulting in a month without menstruation. You can observe or take oral medication under the guidance of a doctor. There may also be other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment.