Do Expired Pregnancy Tests Work?

By Dr. Kenosha Gleaton, OBGYN

Home pregnancy tests were first made available over the counter in 1978. [1-2] Prior to this, finding out if you were pregnant required a trip to the doctor’s office and a lot of waiting around. Fortunately technology has come a long way, and pregnancy tests are now widely available online and in stores, and require far less effort. [2] So, let’s go over why you may want to avoid using an expired pregnancy test, and what else to look out for when stocking up on pregnancy tests. 

When Do Pregnancy Tests Typically Expire?

Unfortunately, some good things do come to an end, including pregnancy tests. While it may seem strange, pregnancy tests and other health and wellness items can expire, so it’s important to check the dates on your products if it’s been a while since you purchased them. [3-4] A product’s shelf life and expiration date will depend on how and where it’s made, but generally, pregnancy tests will expire within a few years after being produced. This is because the components of the test age and evaporate, which can lead to an inaccurate result. [2-4] You should be able to find the date of expiration somewhere on the packaging. 

So, Are Expired Pregnancy Tests Still Effective?

There is a chance that an expired pregnancy test will still produce a result, but there is no guarantee that the result will be accurate, which may lead to a false negative result. Home pregnancy test strips work by detecting a hormone known as human Chorionic Gonadotropin (hCG) in your urine. [3] When an embryo implants into the uterine lining, the body will begin to produce more and more hCG. Pregnancy tests are made using antibodies that will react to the presence of hCG, which is why you’ll see a line in the “test” column if you are indeed pregnant. [2-4] In an expired test, the antibodies will eventually evaporate, causing the test to be ineffective. 

If you notice your pregnancy tests are expired, it’s best to toss them and buy a new pack. You can also visit your provider if you want to confirm or rule out pregnancy. Can you reuse pregnancy tests? Find out → 

How Common Are False Negative Pregnancy Tests?

A false negative result, while still uncommon, is more likely to occur than a false positive. [5-6] A false negative pregnancy test result means receiving a negative result even though you are pregnant. It’s hard to say how often a false negative appears, as the cause of a false negative could be related to user error rather than an issue with the test itself. [5-7] One study found that a false negative test result appeared in less than 1% of cases, while another report states false negatives may appear in up to 5% of cases. [8] 

A false negative result may be caused by a few different factors, including [5-6]:

• Testing too early: hCG levels are fairly low early in pregnancy but rise rapidly. You may need to wait a few more days to get a positive result. 
• Taking the test incorrectly: be sure to follow test instructions exactly
• Checking the result too soon: You should check your results only when the instructions tell you to do so, for the Natalist test, it’s recommended you check the results within 5 to 15 minutes. 
• Diluted urine: Taking a test later in the day or after drinking very large amounts of water may cause a false negative result, especially if you are testing very early. 
• Degraded hCG: In an article from the Washington University School of Medicine, a researcher explains that degraded forms of hCG, called hCG core fragments, increase as pregnancy progresses. [8] If a test antibody binds to this degraded form, there may not be a test color change, causing someone to read the result as a negative. This isn’t thought to happen often but was observed in a small number of cases. [8] 

How Common Are False Positive Pregnancy Tests?

False positive pregnancy tests are very rare, but they can happen. A false positive result could be caused by a few different factors, including [5-6]:

• A chemical pregnancy: A miscarriage or pregnancy loss that occurs very early on, before the fifth week of pregnancy. [9] In this case, someone isn’t exactly receiving a false positive result, but they have experienced an early miscarriage. Unfortunately, chemical pregnancies occur fairly often but happen so early that many don’t realize anything has happened. [9] 
• Certain medications: Some fertility medications can cause a false positive result. If you are taking fertility medications, speak with your provider about using pregnancy tests. 
• Certain health conditions: In some cases, an underlying medical condition could cause a false positive pregnancy result. 
• Evaporation line: Getting a test wet or checking a test result later than the instructions indicate may lead to an evaporation line. An evaporation line is a small, colorless streak that appears over the test line on a pregnancy test. To avoid this, be sure to follow pregnancy test instructions exactly. 

If you are concerned you’ve received a false positive pregnancy test, you should speak with a provider. They can test your blood or perform a vaginal ultrasound to get more information. See examples of what a positive pregnancy test really looks like → 

Always remember to look for a control line on a pregnancy test, especially if you believe you’ve received an inaccurate result. The control line is often marked by a small “c”, and a dark line should appear to indicate that the test is working. If you are using a test that has expired, you should retest using a new, unexpired test, or speak with a healthcare provider. 

Explore Pregnancy Tests & More from Natalist

Pregnancy tests are convenient and useful for getting clear answers about your reproductive health in the comfort of your own home. To ensure you are getting an accurate result, be sure to follow instructions exactly, and ensure that the tests you are using are not expired. You should also check for a control line after taking a pregnancy test. Natalist is proud to offer sensitive, early-result pregnancy tests, which can be found online and in select stores. If you are trying to conceive soon, speak with your provider about prenatal care, including taking prenatal vitamins for women or menstrual cycle supplements to support regular ovulation. Learn more about testing for pregnancy on the Natalist blog. 

References:

1. The Thin Blue Line- The History of the Pregnancy Test. NIH.  Accessed January 2024. https://history.nih.gov/display/history/Pregnancy+Test+-+A+Thin+Blue+Line+The+History+of+the+Pregnancy+Test
2. Gnoth C, Johnson S. Strips of Hope: Accuracy of Home Pregnancy Tests and New Developments. Geburtshilfe Frauenheilkd. 2014;74(7):661-669. doi:10.1055/s-0034-1368589
3. Eskandar MA, Al-Shahrani M, Shaamash A, El-Emain M, Al-Ahmad M, Payodon B. Early Maternal Serum β-human Chorionic Gonadotropin Measurements After ICSI in the Prediction of Long-term Pregnancy Outcomes: A Retrospective Cohort Analysis. J Clin Med Res. 2011;3(1):30-35. doi:10.4021/jocmr477e
4. Guidance for Over-the-Counter (OTC) Human Chorionic Gonadotropin (hCG) 510(k)s - Guidance for Industry and FDA Reviewers/Staff. Center for Devices and Radiological Health, Office of Product Evaluation and Quality. FDA-2020-D-0957. July 2000. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-over-counter-otc-human-chorionic-gonadotropin-hcg-510ks-guidance-industry-and-fda
5. Pregnancy Tests. Cleveland Clinic. November 2022. https://my.clevelandclinic.org/health/diagnostics/9703-pregnancy-tests
6. Home pregnancy tests: Can you trust the results? Mayo Clinic. December 2022. https://www.mayoclinic.org/healthy-lifestyle/getting-pregnant/in-depth/home-pregnancy-tests/art-20047940
7. Adrianna Z Herskovits, Yigu Chen, Niloofar Latifi, Robert M Ta, Gila Kriegel, False-Negative Urine Human Chorionic Gonadotropin Testing in the Clinical Laboratory, Laboratory Medicine, Volume 51, Issue 1, January 2020, Pages 86–93, https://doi.org/10.1093/labmed/lmz039
8. Bhandari, Tamara. Flaw in many home pregnancy tests can return false negative results. April 2019. Washington University School of Medicine St. Louis. https://medicine.wustl.edu/news/flaw-in-many-home-pregnancy-tests-can-return-false-negative-results/
9. Chemical Pregnancy. Cleveland Clinic. December 2021. https://my.clevelandclinic.org/health/diseases/22188-chemical-pregnancy

Dr. Kenosha Gleaton is board-certified in gynecology and obstetrics and is the Medical Advisor of Natalist. She received her MD from MUSC and completed her residency at Carolinas Medical Center in Charlotte, NC.