Modern home pregnancy tests are fairly reliable, so most of the time, getting a negative pregnancy test means that you are probably not pregnant. There are a few exceptions when a pregnant woman could theoretically get a false negative on her pregnancy test:
- Testing too early
Pregnancy tests will always be more accurate if you wait until your period is due or late before testing. Even a test marketed as giving an early answer can give you a false negative if you test before your menstrual period is due. If your period is already late, you can wait a week and repeat the test. Errors in using the test
If you make a mistake while using the test, such as not using enough urine on the test stick, you may get an incorrect result. But usually if the control line shows up, your test result should be accurate.Using diluted urine
In early pregnancy, it is possible that drinking a lot of water and testing late in the day could affect the accuracy of the test. Most pregnancy test manufacturers recommend testing first thing in the morning. But this should only be a factor in the first few days after your missed menstrual period; after that, usually even a test later in the day should give a positive result.
If you get a negative pregnancy test after having previously had a positive pregnancy test, you may be having a miscarriage -- especially if you are also having vaginal bleeding -- but there is a slim chance that one of the above issues might be affecting the accuracy of your second pregnancy test if you are still in very early pregnancy. When in doubt, you should call your doctor's office for advice.
If your period is late but your pregnancy tests are negative, there are a number of possible explanations for why your period might be late. Call your doctor for a blood test if you believe you are pregnant.
Source:
US Dept of Health and Human Services, "Pregnancy Tests: Frequently Asked Questions." National Women's Health Information Center Apr 2006. Accessed 17 Nov 2008.
