Whether the period is early or delayed is not good, the onset of menstruation should be within the normal range to be best. The normal menstrual cycle is 21-35 days. If the period is significantly early and shortens to within 21 days, it is significantly early. If the menstrual cycle is greater than 35 days, it is a significant delay. In either case, the appropriate treatment should be performed. Significantly early menstruation is a kind of frequent menstruation, an abnormal uterine bleeding, and should be examined accordingly, if necessary with a hysteroscopy. In the case of significantly delayed menstruation, a sex hormone test should be performed to consider whether there is polycystic ovary syndrome or other endocrine abnormalities of the ovaries, and the appropriate treatment should be given.