Pregnancy
1. How do pregnancy tests work?
2. Negative results from pregnancy tests.
3. Can anything interfere with pregnancy test results?
PURCHASE A PREGNANCY TEST
Pregnancy tests look for a special hormone in the urine or blood that is only there when a woman is pregnant. This hormone, human chorionic gonadotropin (hCG), can also be called the pregnancy hormone.
The pregnancy hormone, hCG, is made in your body when a fertilized egg implants in the uterus. This usually happens about 6 days after conception. But studies show that the embryo doesn't implant until later in some women. The amount of hCG increases drastically with each passing day you are pregnant.
Many home pregnancy tests claim they can tell if you're pregnant on the day you expect your period. But a recent study shows that most don't give accurate results this early in pregnancy. Waiting one week after a missed period will usually give a more accurate answer.
I got a negative result on a home pregnancy test. Might I still be pregnant?
Yes. So, most HPTs suggest women take the test again in a few days or a week.
Every woman ovulates at different times in her menstrual cycle. Plus, embryos implant in the uterus at different times. So, the accuracy of HPT results varies from woman to woman. Other things can also affect the accuracy.
Sometimes women get false negative results (when the test says you are not pregnant and you are) when they test too early in the pregnancy. Other times, problems with the pregnancy can affect the amount of hCG in the urine.
If your HPT is negative, test yourself again in a few days or 1 week. If you keep getting a negative result but think you are pregnant, talk with your doctor right away.
Most medicines, over-the-counter and prescription, including birth control pills and antibiotics, should not affect the results of a home pregnancy test. Only medicines that have the pregnancy hormone hCG in them can give a false positive test result. A false positive is when a test says you are pregnant when you're not.
Sometimes medicines containing hCG are used to treat infertility (not being able to get pregnant). Alcohol and illegal drugs do not affect HPT results. But women who may become pregnant should not use these substances.
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