If the early pregnancy test paper does not detect pregnancy, it may be caused by the following reasons: Firstly, the time of pregnancy is relatively short, at this time the positive result will only appear by drawing blood to check blood HCG, while urine HCG is relatively not as high as blood HCG concentration, so the positive rate appears is not high, it is recommended to check after a period of time, then the positive result will appear. Secondly, it is possible that the early pregnancy test paper has expired, or the packaging of the early pregnancy test paper is broken and contaminated by the corresponding chemical agents, so that the detected results will be negative in the clinical situation, so before doing the early pregnancy test, you must know whether the packaging is complete, and it is best to avoid chemical agents to avoid contamination and cause inaccurate detection.