If you have not had your period for a month, first of all, you should exclude whether you are pregnant or not, because pregnancy does not exist in menstruation. If pregnancy is ruled out and you haven’t had your period for a month, for example, during puberty there may be a long delay, possibly two or three months, because the endocrine hormones in your body are not yet well developed, so it is advisable to be patient and observe again, as it will not affect your health. After puberty, if you have not had your period for a month at the age of 18 or more, there may be many reasons. For example, recent stress, staying up late, mood factors or eating cold, stimulating food, including endocrine hormone imbalance, sudden changes in the environment, may cause menstruation not to come. If your period is delayed for 7-10 days, it is normal. If it does not come for more than 10 days, it is recommended that endocrine hormone tests, including ultrasound, be performed to see the thickness of the endometrium, and depending on the situation, certain oral menstrual drugs can be taken to promote menstruation.