If I see a very light line on my pregnancy test, am I pregnant?
A home pregnancy test measures the hormone human chorionic gonadotropin, also known as hCG. For a pregnancy test to show positive, your body must be producing a level of hCG that the test can detect. Not all pregnancy tests are the same, however. Some tests are more sensitive than others and will show a positive result earlier than tests that are less sensitive.
If your test shows only a very light line, the test itself may not be very sensitive. The box that the test came in should indicate somewhere what its sensitivity is. Sensitivity is measured in IU/L, which stands for milliInternational Units per Liter. A very sensitive test may have a sensitivity of 20 IU/L, whereas a test that is not as sensitive might have a sensitivity of 50 IU/L.
You may also get a faint positive if you are not as far along as you think you are. If you suspect that this is the cause of the light line, taking another test in two or three days can give you more exact results.
Finally, if you have a very light line and then have a completely negative result a few days later, you may have had an early miscarriage.