When you arrive at the ovulation period, you can’t detect ovulation with ovulation test paper, mainly consider the following two possibilities: First, the patient’s detection time is not suitable, although the patient is detected at the ovulation period, but the patient’s ovulation does not necessarily occur at the ovulation period. Because female ovulation is affected by various factors, such as emotional changes, seasonal changes, increased work and study stress, excessive weight loss and various other reasons, there is advancement or delay, which can occur during ovulation or during the safe period. If a woman does not ovulate within the ovulation period, ovulation will definitely not be monitored with ovulation test strips. Secondly, consider that the quality of the test strips used by the patient is not good or the method of detection is not appropriate, because ovulation test strips are bought in pharmacies and the quality varies, if the quality bought is not good, it can be undetectable, or the patient’s monitoring method is not correct, there can also be false negatives.