Drugstore shelves today are packed with tests with labels like "early result" or "early response," some of which may be able to tell you're pregnant up to five days before you've even missed your period -- as soon as 10 days after you've ovulated. That's because these tests may be more sensitive than others at detecting levels of human chorionic gonadotropin (hCG) in your urine. hCG is a hormone that your body starts producing shortly after you've conceived. You should always read the label information to get a true sense of how accurate it is, and when. Even "early result" tests are more precise the later you use them (like the day you expect to get your period), since hCG levels may be tricky to detect so early into pregnancy. If you get a negative test result but still haven't gotten your period a few days later, it's a good idea to test again. You likely got what's called a "false negative" the first time -- where the test says you're not pregnant, but you actually are.