Home Pregnancy Test False Positive: What It Means

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If you’ve taken your pregnancy test at home and got a positive result, you probably assumed you are pregnant. Given the claimed 99% accuracy rate, you may have been shocked to later learn this result was actually a false positive. Here’s a look at the many things that can cause a home pregnancy test false positive.

1. Improper testing
This is one of the most common causes for a home pregnancy test false positive. Always read the instructions completely when you take a pregnancy test at home, as they will explain when the results are no longer valid and how they should be read. Some tests will actually produce a positive test result if you read if too long after the valid time. Use a timer after you perform the test so you know when your results will be right. This problem can also happen if you try to double-check your results later. If you’re upset about a negative result at 3 to 5 minutes and go back twenty minutes later, you may get a false positive.

2. Evaporation line
Some at-home tests create an evaporation line along the testing line of the strip. This is also described as a watermark, but should not be interpreted as a positive result. If the strip does not change color and have a line of color at the end of the testing time, it is not a positive. If this is a problem for you, try a different brand, retest in a few days or try a digital test.

3. Chemical Pregnancy
Because at home pregnancy tests are able to detect the pregnancy hormone in very small amounts, a chemical pregnancy may cause a false positive. Chemical pregnancies are really just early miscarriages and research has shown that up to 50% of all first pregnancies end with a miscarriage. If you get a false positive, it may be the result of a very early pregnancy that ended and you’ll still get your period.

4. False positive from medications
There are certain prescription medications that can cause a false positive as well. If you’re receiving hCG therapy, for example, your at home pregnancy tests may not be accurate because your urine may contain small amounts of the hormone that isn’t related to a pregnancy.

5. False positive from medical conditions
Certain medical conditions can also cause a false positive on an at home pregnancy test. These conditions are rare, however, but include cancers like choriocarcinoma that create an elevated hCG level.

6. Defective test
A defective or expired at home pregnancy test can also create a false positive. Make sure the test is not expired before you use it and double-check a positive result by following up with your doctor.