Among the causes of a false negative pregnancy test, the most common one is performing the test too early. If you don’t wait until the indicated day to take the test, the hCG hormone levels may still be too low to be detected even though pregnancy is present.
Another possible reason for a false negative urine pregnancy test is that the test was performed incorrectly. It´s important to follow the manufacturer's recommendations and perform the test with the first urine of the day, as well as to use a test that is not expired or in poor condition.
Also, some medications can interfere with the pregnancy test, which can lead to erroneous results.