A light mark on a pregnancy test after it has been left to dry for a long time does not mean pregnancy. The test result of a pregnancy test stick should be observed within 5 minutes after the test. If it is left for a long time and observed for more than 5 minutes, the test result is not allowed, and whether there is a light or a deep mark, it cannot determine whether it is pregnant or not. A pregnancy test with a light mark after being left to dry for a long time has no clinical reference value because it will trigger a false test and the possibility of a false positive. The main reason for the false test is the testing time, because the mechanism of the pregnancy test is to determine the level of human chorionic gonadotropin in the urine, and if the test takes too long, the urine test paper will be affected by uric acid in the urine and so on, and there will be certain false negative or false positive results. In addition, the pregnancy test will lose its normal testing efficacy after being left to dry for a long time, which will also lead to inaccurate test results. You can take a morning urine test with a pregnancy test stick the next day and read the test result within the specified time according to the instructions. If necessary, a gynecologic ultrasound can be performed to determine if the pregnancy is normal in utero.