Will a pregnancy test show fals positive taking it right after unprotected intercourse?

A pregnancy test taken immediately after unprotected intercourse will almost certainly give a false negative result, if any result at all, since it can take several days for the levels of pregnancy hormones to rise sufficiently to be detected by a home pregnancy test. For the most accurate results, it is recommended to wait at least one week after the expected date of missed period before taking a home pregnancy test.