If the ovulation monitoring test changes from strong positive to weak, it usually indicates ovulation. Ovulation test strips can detect peak luteinizing hormone in the urine to determine the time of ovulation. If the concentration of luteinizing hormone in urine is more than 30 IU/L, it is positive, indicating that the peak of luteinizing hormone in blood has already appeared, and ovulation is usually imminent in about 12 hours, so you can make good use of the time to arrange intercourse to help conception success. After ovulation, the blood luteinizing hormone level will drop rapidly and the ovulation test paper will change from strong positive to weak positive, indicating ovulation. In addition to monitoring ovulation with ovulation test strips, you can also monitor ovulation by ultrasound. When the follicle reaches about 18mm in diameter and has a certain tension, it is considered to have reached the mature stage. After ovulation, if the follicle suddenly disappears or shrinks and a small amount of pelvic fluid is seen, it indicates ovulation, which can accurately determine the time of ovulation.