It is best to take a pregnancy test from the first day of your missed period for an accurate result. Some very sensitive tests can detect pregnancy a few days before the missed period, but testing too early increases the risk of a false negative. For the most reliable result, waiting about a week after the missed period is recommended. If you are unsure about when your period is due or have irregular cycles, taking the test about 21 days after unprotected sex is advised. Testing first thing in the morning can also improve accuracy because hormone levels in the urine are more concentrated then.