If the follicle disappears on ultrasound monitoring, or if there is a small amount of free fluid in the pelvis and the follicle is <5cm, this indicates ovulation. Some women monitor ovulation by ultrasound during pregnancy preparation. The advantage is that it is more accurate and intuitive, but the disadvantage is that it is more troublesome to go to the hospital frequently. If a woman has a menstrual cycle of about 30 days, she can start monitoring from about the 10th day of menstruation. When the follicle grows to about 1.3cm, she can do monitoring once every two days, when it grows to about 1.7cm, she can do monitoring every day, and when the follicle grows to 2cm, she will ovulate and it is recommended to arrange sex. In addition to ultrasound to monitor ovulation, you can also observe the changes in leucorrhea and body temperature to determine the ovulation situation, such as egg-white leucorrhea after ovulation, which can appear in a light greenish color, and the body temperature will also rise, and the LH test paper can appear strongly positive. Usually women can test according to the above methods and increase the number of sexual intercourse before and after ovulation to increase the chance of conception.