The pregnancy test can detect pregnancy at night, but the accuracy may be reduced due to various reasons during the day. And the pregnancy test itself is not 100% accurate. The pregnancy test has an accuracy rate of about 85%-95% when used correctly. The pregnancy test is used to determine whether or not a woman is pregnant by testing the HCG value, or human chorionic gonadotropin, which is secreted by the placenta and runs throughout the body in the bloodstream, so a woman can choose to urinate and test for pregnancy with a pregnancy test. The amount of water you drink during the day may affect the concentration of HCG in your body. If you drink a lot of water during the day, it will cause the urine to be diluted, resulting in inaccurate results when testing at night, and possibly false negative results. The reason why morning urine is chosen is that it is more concentrated and contains higher HCG values compared to other times of the day, so if you want to choose a pregnancy test, it is recommended to choose morning urine for the test. In addition to the influence of water consumption, taking some medications, such as certain birth control pills and ovulation pills, as well as diseases, can also lead to false-positive results. If the test is chosen too early, there is not enough HCG production in the body, resulting in insufficient HCG in the urine, and the test result may be a false negative at that time. If a woman is in a hurry to take a pregnancy test, she can go to the hospital in time for a blood test, which is more accurate.