The one where you start getting contractions. You'll know for sure you're pregnant then. Otherwise, I'm not sure. Clear Blue is supposed to be popular?
Consider all positive test results to be accurate. Different brands will be able to detect a pregnancy earlier than others. A negative result could mean the hormone changes tested for aren't at high enough levels...yet. You should follow directions provided with the test, and if you still don't have your period in a week, try again.
