There are many common reasons for not detecting pregnancy, there are the following factors: 1. If a pregnant woman uses a pregnancy test or a pregnancy test stick on her own and does not detect pregnancy, mostly because the pregnancy test supplies used have expired, the pregnancy test stick or the pregnancy test paper used is contaminated by dust, sewage, etc., and loses its normal detecting role, there can be false negative results, which also means that the pregnancy cannot be detected. If a pregnant woman chooses to take the test in the afternoon or evening, the test results will be affected by the consumption of certain foods or drugs, which will also cause certain interference in the test results, and the pregnancy test may not be detected. It is recommended that pregnant women can choose to go to the obstetrics and gynecology department for a blood pregnancy test after a week of menopause to make a clear diagnosis.