Under normal circumstances, ovulation lasts for about 10 days, and the exact timing varies depending on each person’s menstrual cycle. For women with regular menstrual cycles, the day of ovulation is the 14th day before the next menstrual period. The day of ovulation plus the 5 days before and 4 days after the day of ovulation is called the ovulation period, which is about 10 days in total. Ovulation can occur at any time during the ovulation period and the egg cells will live in the body for 1-2 days after ovulation, so sex during this period is most likely to result in a fertilized egg and pregnancy. The period of ovulation can vary depending on the menstrual cycle and should be analyzed on a case-by-case basis. In the case of women with irregular menstrual cycles, ovulation cannot be determined by calculations, but can be determined by ovulation test strips or ultrasound follicle monitoring. In addition, although it is easiest to get pregnant during ovulation, it does not mean that you will not get pregnant during periods other than ovulation, so if you do not plan to get pregnant, you should use good contraception.