The follicles are mainly monitored by ultrasound, which monitors the growth and development of the follicles, usually on the eighth day of menstruation, the fertility doctor will do an ultrasound test to see if they have reached the status of a dominant follicle, i.e. 10mm. if not, they will usually come back every two days, and when the follicles grow to 16mm they will be checked once a day, and when the follicles grow to 18mm or more they will be checked twice a day, and then the time of ovulation will be determined. Ultrasound follicle monitoring is the most common method used by fertility doctors to continuously monitor follicle growth and development. During the IVF process, follicle growth and development is directly related to the ability to retrieve mature eggs, which affects the success rate of IVF, all of which require the patient’s cooperation.