There are probably many reasons why pregnancy tests are not accurate. The accuracy of the pregnancy test stick are more than 90%, if the use of the process happens to be in the inaccuracy of the range of the individual is not allowed, but can not negate the accuracy of the pregnancy test stick, need to find out the specific reasons. 1, the pregnancy test stick is mainly used for detecting early pregnancy, generally in about 40 days of pregnancy, the effect is the best, if the test time is too early, because of the HCG value in the urine is relatively low, it is possible that there is a negative If the test time is too early, because the HCG value in the urine is relatively low, there may be negative or weak positive situation, you need to re-test in a few days or with the examination of blood HCG, the accuracy rate is higher. 2, if the use of improper, there will be inaccurate results, you need to read the instructions, the correct operation, the accuracy rate is higher. 3, if you do not save the bad, the failure of the test stick, the test results will be incorrect, but it can not be denied that the accuracy of the pregnancy test stick.