If you use a pregnancy test after your period has been delayed for 2 days and you find only one red bar, it means that the result of the test is negative. There are two possibilities: First, you are not pregnant. Second, you are already pregnant. As the pregnancy time is relatively short, so the HCG concentration in the urine is not high, do urine test paper can not be detected, in this case you can continue to observe, if after 2-3 days of menstruation normally come, it does not matter. If after 2-3 days of menstruation still did not come, you need to use the morning urine to do another urine pregnancy test or go to the hospital to draw blood to check chorionic gonadotropin, blood test results will be more accurate. It cannot be ruled out that some women do not use the pregnancy test correctly, which may also lead to abnormal results.