Aunt refers to menstruation, and ovulation usually occurs about 14 days before the next menstrual period, and the timing of ovulation varies from one menstrual cycle to another, so it is important to analyze specific problems. If the menstrual cycle is 28 days, ovulation occurs in the middle of the two menstrual cycles, which means that the second menstrual period is pushed back 14 days to the time of ovulation. If you have your period on the 2nd, you will ovulate around the 16th. If your menstrual cycle is not 28 days long, you need to use your menstrual cycle to roughly calculate the time of your next menstrual period, and then the time of your next menstrual period is about 14 days ahead of the time of ovulation. Generally the follicular phase is not fixed, the length of menstruation is related to the follicular phase, and the luteal phase is generally more fixed. If there is no pregnancy, the corpus luteum will contract after 14 days and then menstruation will occur. So when calculating the ovulation period, always push forward 14 days from the time of your next period.