For women who have a normal menstrual cycle and typically menstruate once every 28-30 days, it is most appropriate to monitor the follicles on days 8, 10, 12, and 14 of the menstrual cycle. The reason patients need to go to the hospital four times is because a normal woman’s menstrual cycle is divided into the follicular phase and the luteal phase, and the follicular phase is around 14 days, so on the 8th day of menstruation, the size of the follicle is about 8mm, by the 12th day the size of the follicle is 10mm, and by the 14th day of menstruation it reaches the peak of the preovulatory phase, and the follicle grows to about 18mm, which is when the follicle has matured and is about to be ovulated, and this is when it’s time for the last monitoring of the Follicles are monitored for the last time. If you don’t see the follicle drain directly, you won’t know if the follicle didn’t grow this cycle or if it didn’t drain, so follicle monitoring needs to be done a total of 3-4 times. This is so that you can gradually see a follicle grow and be sure that the follicle is developing normally and has been drained. Because women only ovulate once a month, it is important to monitor the entire process of growth and development. If there is a slight delay in the middle of the process, ovulation drugs can be added to promote growth and help complete the normal development of the follicle.