Early pregnancy test paper test three times negative, but is pregnant, generally due to the shorter time of conception early pregnancy test paper did not detect, early pregnancy test paper used in the wrong way, early pregnancy test paper expired or early pregnancy test paper moisture by the pollution are possible. 1. Conception time is short: early pregnancy test paper can not be detected, early pregnancy test paper needs to be about 15 days from the most recent coitus, with the morning urine test is more accurate, if less than 15 days or not with the morning urine test, it is possible to detect the pregnancy. 2. Early pregnancy test paper is not used in the right way: for example, urine specimens to take a small amount or placed in the wrong position may not detect pregnancy. 3. Expired pregnancy test strips: If the pregnancy test strips are expired, then the sensitivity of the test strips will be reduced, and it is easy to detect the pregnancy. 4. Early pregnancy test paper failure: early pregnancy test paper moisture or by some drugs and chemicals contamination, resulting in early pregnancy test paper to lose efficacy will also appear early pregnancy test paper negative results. If you have had sex and delayed menstruation, early pregnancy test can not be detected, then you can take a blood test chorionic gonadotropin to detect whether the pregnancy, blood test is relatively accurate, generally about 7 days from the coitus can be measured. After determining pregnancy, you should go to the hospital regularly for maternity checkups, and find abnormalities at any time, so as to avoid adverse consequences.