Normally, if the egg is not fertilized 12-48 hours after ovulation, the apoptotic mechanism will be activated and it will die naturally. The normal menstrual cycle consists of the menstrual phase, the follicular phase, the ovulatory phase and the luteal phase. During the follicular phase, the follicular cells in the ovary begin to develop gradually, culminating in one dominant follicle becoming fully developed and ovulation occurs. After ovulation, the egg waits in the fallopian tube to meet a sperm. If it does not meet a sperm within 1-2 days, it will senesce and die; if it can wait for a sperm, it will have a chance to unite with the sperm to form a fertilized egg, which will then be deposited in the uterine cavity, and then pregnancy will occur. If you are a woman planning to get pregnant and had regular periods in the past, you can calculate your ovulation period, or you can go to the gynecology department of a regular hospital for ultrasound monitoring to determine the ovulation period through the development of the follicles, and then make reasonable arrangements for coitus during the period of ovulation to improve the chances of conception.