Most women ovulate around 5-7 days after the emergence of the dominant follicle. In the early stage of follicular development, there are usually several small follicles developing at the same time, but only one follicle will develop and expel each month, and this is the dominant follicle. When the dominant follicle reaches 18-23mm, it will become a mature follicle and may ovulate at any time. Usually, the dominant follicle can be seen with ultrasound monitoring of follicle development a few days before ovulation, and can develop into a mature follicle and be expelled 5-7 days later. The quality of sperm and eggs around the time of ovulation is good and the relative embryonic viability will be good, thus facilitating pregnancy.