It can cause a false positive result or a faint line on a pregnancy test because the brief pregnancy produces a small amount of hCG in your body. You made a mistake in taking the test.

Pregnancy test (PT) strips are thin, flexible strips that you dip into a ... If the hormone is detected, you’ll see a colored line or symbol appear in the test window, indicating a positive result.

Pop princess Katy Perry has revealed the unique place she keeps her positive pregnancy test. The test was the one that first told her she was pregnant with her now 4-year-old daughter, Daisy Dove.