Ovulation test strips can no longer be used once they expire, mainly because after the expiration date of ovulation test strips, even if the concentration of luteinizing hormone in the urine is high, it will not be detected as a positive result or a strong positive result, and if you test the test strips when they are expired, it is likely that you will misjudge the time of ovulation. Check if the test paper is expired before using ovulation test paper, if it is expired, it should not be applied. Also, if the test paper is contaminated with certain chemicals, it should not be applied and may also give incorrect results. If the packaging of the ovulation test strips is broken, they may also be contaminated accordingly and it is best not to apply them either. Before using ovulation test strips check the date of manufacture, check if the packaging is broken or find out if it has been contaminated with other chemicals, if any of these things are present, it should not be applied.