What's the deal with false positives?

false positive pregnancy test

When it comes to pregnancy and ovulation testing, understanding your cycle and health is the key to success. Most home pregnancy tests like Stix are over 99% accurate, but that’s not to say false results aren’t possible. So what is the deal with false positives? What are they, why do they happen, and how can we do our best to avoid them? 

What is a false positive?

A false positive happens when your pregnancy test shows a positive result but you are actually not pregnant. It’s hard to distinguish a false positive from a real result so, just to be sure your results are accurate, Stix provides two tests for a peace of mind in trusting your results. 

False positives are much less common in pregnancy testing than false negatives. This is because it’s very rare for your body to produce hCG, the hormone that your test detects, if you’re not pregnant. In a study that tested 27 different kinds of at home pregnancy tests, false negative results were displayed 48% of the time.


What causes false positives?

The most common causes of false positives have to do with traces of hCG in your urine that the test mistakes for pregnancy. For example, if you are taking fertility medications containing hCG, this might affect the accuracy of your results. Other medications that can increase the risk of a false positive include some anti-anxiety medications, antipsychotics, Parkinson’s disease medications, and antihistamines. Certain health conditions can cause your hCG levels to rise, even if you’re not pregnant, including ovarian cysts, kidney infections and UTIs, and pituitary gland disorders.

Additionally, taking a test too soon after a recent miscarraige or chemical pregnancy can detect hCG levels that have remained in your body. This test will show a positive result, but only because the pregnancy hormone is still being flushed from your body. Similarly, an ectopic pregnancy will most likely give you a positive test result. Ectopic pregnancies still produce the hCG hormone, but are developed outside of the uterus. If you think you might be having one, see your primary care physician immediately. 

All tests are different, but a lot of the time false positives are caused by problems with the test or issues interpreting your results. One likely cause is evaporation lines. For most brands, a positive result will be indicated with two lines and a negative result will show one. An evaporation line looks like a faint, colorless line that appears to be a positive result. To avoid this, read your test instructions and wait to look at your results no earlier or later than they say to. Also, it’s important to make sure that your test is not expired. Expired tests aren’t as effective in detecting hCG levels and are more likely to produce inaccurate results.  

What can we do to avoid false positives?

The last thing we need when taking a pregnancy test is to worry about whether we can trust our results or not. Two easy and simple things you can do to avoid false results are reading the instructions and checking the expiration date. Taking a test first thing in the morning before you’ve had anything to drink will lead to more accurate results as your urine is more concentrated and less diluted. 

The most important thing you can do to limit your chances of a false pregnancy test result is to get in the know about how they work. This includes when to take them relative to intercourse, how long to wait to look at your results, what time of the day to take one, and so much more. Testing for pregnancy isn’t as simple as any of us thought! Check out our definitive guide to pregnancy tests for tips and tricks on how to get the most accurate results.

It’s equally important to get informed about your body and your cycle. Taking a test too early or too late in your cycle will affect your results. Learning more about your cycle will also help you understand when you’re most and least likely to conceive. To do this, we find it helpful to regularly take ovulation tests and read up on resources about your body.

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