What does the evaporation line on a pregnancy test indicate? 

An evaporation line mimics a positive pregnancy test. A second line shows up when in fact you are not pregnant. An evaporation line can give you a "false positive" pregnancy test.

If you don't follow the instructions and you wait longer and read the result after the suggested time, the results are unreliable. Waiting longer than the suggested time can lead to a second line showing up which may not be hCG. That's an 'evaporation line,' which is not a positive test and has nothing to do with hCG being present in the urine. 

This is what we suggest:

1. Read the manufacturer's instructions carefully.
2. Wait the suggested amount of time and read the test results. 
3. If there is a negative result after the suggested time, throw the test away to prevent any confusion. 
4. Re-reading the test at a later time will confuse you. 
5. If the test is only faintly positive after the suggested amount of time, chances are that you could be pregnant. The hCG in your urine may have been too low to give you a stronger positive result. If there is a faint line, it's suggested that you repeat the test a couple of days later.