A menstrual period lasting 3-7 days is considered normal, and the majority of menstrual cycles are around 28-30 days, so as long as you can have a period between 21-35 days, it is also considered a normal menstrual cycle. A woman’s menstrual cycle is directly related to the ovulation function of the ovaries. In the case of early ovulation, the menstrual cycle will naturally advance. If ovulation is delayed or even absent for a long period of time, the menstrual cycle will be pushed back or amenorrhea will occur. There are many factors that affect the ovarian function, such as emotional stress or fatigue, which can lead to delayed ovulation. Therefore, many women experience occasional changes in their menstrual cycle, which do not require any treatment as long as the changes are not particularly noticeable. A woman’s menstrual cycle is mainly related to the shedding of the endothelium. As long as the endothelium is normally shed and the uterus can contract normally, the menstrual cycle can be cleared within a normal period of time.