How long do you have to wait before taking a pregnancy test?

According to the American Pregnancy Association, home pregnancy tests are most accurate after the beginning of the first missed period, or around two weeks after conception. Blood tests performed at a doctor's office can detect pregnancy even earlier, at around seven to 12 days post-conception.

The Department of Health and Human Services recommends waiting a week after a missed period to perform a home test to minimize the chances of getting a false negative result. Both blood and urine tests detect the hormone human chorionic gonadotropin (hCG), and it takes some time to build up in the blood and urine after conception.