When using ovulation test strips to monitor ovulation, if it goes from weak positive to strong positive to weak positive, it indicates that ovulation may have occurred. Luteinizing hormone spikes are a reliable indicator of ovulation, and ovulation test strips use this principle to predict ovulation by monitoring luteinizing hormone levels in the body. The higher the peak of luteinizing hormone, the higher the positive level of ovulation test paper. The higher the peak of luteinizing hormone, the higher the level of positive ovulation test paper. After ovulation, the peak of luteinizing hormone drops rapidly, so the luteinizing hormone test paper will change from strong to weak positive. Ovulation test strips have certain limitations and may miss the time to monitor strong positive to weak positive even if there is ovulation because of the uncompact monitoring time. If the ovulation test paper keeps showing weak positive and no strong positive, it usually indicates no ovulation. In addition, if the ovulation test fails, it is recommended to monitor ovulation together with ultrasonography for more accurate monitoring.