You should wait to take a pregnancy test until the week after your missed period for the most accurate result. If you don't want to wait until you've missed your period, you should wait at least one to two weeks after you had sex. If you are pregnant, your body needs time to develop detectable levels of HCG. You’re more likely to get an accurate result if you take the test in the morning. This is especially true if your period is not yet late, or if your period is only a couple days late. At-home pregnancy tests work by detecting the hormone human chorionic gonadotropin (hCG) in your urine. Unless you get up in the night to pee often (or you drink water throughout the night), your urine is more concentrated when you first wake up. This usually means that the amount of hCG is a bit higher, and you’re more likely to get a positive result if you’re pregnant. However, you can still take a pregnancy test in the middle of the day, or even at night. You’re just more likely to get a false-negative, especially if your period isn’t that late, and especially if you’ve been drinking a lot of water and your urine is diluted.