Ovulation usually occurs about 3 days before and after the day of ovulation. In women with a normal regular menstrual cycle of 28 days, the day of ovulation is usually about 14 days before the next menstrual period. Ovulation is often predicted clinically by various methods. The first is basal body temperature measurement. In women with biphasic body temperature, the basal body temperature (BBT) is lower on the day of ovulation or 1 day before ovulation. The basal body temperature starts to rise 1-2 days after the release of luteinizing hormone (LH) and lasts for about 10 days. After ovulation, the body temperature can rise by 0.3℃-0.5℃ due to the influence of progesterone, and on the day of menstruation, the body temperature drops again. It is recommended to use a mercury thermometer to measure the basal body temperature in a quiet state every morning before waking up, this method is simple and economical. Next is ovulation test paper monitoring, urine LH test paper measurement is (+), usually about 24-36 hours will be ovulated. In addition, follicles can also be monitored continuously by ultrasound testing as they approach ovulation. In addition, it is recommended that couples preparing for pregnancy have intercourse on the day of a positive LH and 1 day thereafter, and if intrauterine insemination is planned, the procedure should be performed on the morning of the 2nd day after a positive LH.