What are pregnancy tests?

Home pregnancy tests are amazing. These small little inventions can help you to know about one of the happiest moments of your life. But are these tests 100% reliable?

Can an expired pregnancy test give you a positive pregnancy result and how reliable they are? All these answers will be answered in this article.  The one thing that you need to consider when you are going to a drug store to get a pregnancy kit is the expiration date. Although the pregnancy kit can last as long as two to three years, and expired pregnancy test or kit can give you false hope of pregnancy or even a negative result that may hamper your baby if you don't take care. [1]

See: What To Do After Positive Pregnancy Test

Do Pregnancy Test Really Expire?

There are two fundamental types of pregnancy tests: blood and urine. Each one tests for the hormone known as human chorionic gonadotropin (hCG). But only one type of test expires. Blood pregnancy tests don't expire because diagnosis happens in a lab as opposed to at home. You can get one in a physician's office, where they'll draw a blood sample that is sent out for testing.

The more common urine pregnancy tests, which you can pick up at your neighborhood pharmacy, can expire. The way pregnancy tests work is they're coated in a unique sort of lab-made antibody. Normally, antibodies are proteins that our immune systems make to fend off infection and disease, such as the flu. But we could even synthesize antibodies in the laboratory for several unique kinds of tests that could diagnose everything from infectious diseases. The antibodies in home pregnancy tests respond specifically to hCG, but will gradually evaporate and become less effective with time.

Pregnancy tests can last for two to three years. However, this doesn't imply that the test will last for two years after you purchase it. It might have spent a substantial amount of time sitting on a store shelf. Thus, you must always check the expiration date on the package to be sure. Certain conditions may also affect how fast pregnancy tests perish. It's usually suggested to store pregnancy tests at room temperature, or at least between 36 and 86 degrees Fahrenheit.

The pregnancy test is mainly a device that contains chemicals that can measure the levels of hCG in the urine. The chemical used in the pregnancy test is known as the hCG antibody, and one of the main reasons for false pregnancy tests is that this antibody degrades or breaks down. Thus, you may get an inaccurate test result. [2]

See: Home Pregnancy Test With Salt & Urine

When does a pregnancy test expire?

The expiration of pregnancy tests entirely depends on the brand of the test kit. Mostly the lifespan of the test kit is almost 2 to 3 years, which may vary depending upon the brand or manufacturer of the test kit. This is similar to why many pharmaceutical products expire. Mostly the cheaper test kit expires faster than the expensive ones. The expensive kits may work fine, even after a few months of the expiry date, but it is always advisable to use a test kit that is at least two or three months before the expiry date.[3] 

See: Cloudy urine during pregnancy causes & treatments

Does an expired pregnancy test kit still work?

Yes, an expired pregnancy test may work in certain rare instances, but it will mostly give a false positive. This means you won't be pregnant, but the result will show that you are pregnant. If you think that an expired test gives a false negative, the answer to this question is also yes. The reason for this is that an expired pregnancy test is not sensitive enough to judge the levels of hCG in the urine, and thus, it can give a false negative as well as false positive. Both these results can be dangerous for your mental and physical health. A false positive will give you false hope of pregnancy, and you may be mentally drained after receiving the true result. On the other hand, a false negative can make you neglect your health as well as the health of the fetus, which can lead to premature birth or even death of the baby. [4]

See: Calculate Your Pregnancy By Months, Weeks and Trimester

What happens is you use expired pregnancy test?

What to expect when you use an expired Pregnancy test?

An expired pregnancy test can provide you with four main results, and it can be any one of the following:

- A true positive, a true negative, a false positive, and a false negative. 

- A false positive can be because of any of the following reasons:

- Ectopic pregnancy: This means that the zygote did not get implanted in the uterus. Instead, it got implanted in other regions like the fallopian tube. This can be quite dangerous for women as it can lead to heavy bleeding and pain in the lower back.[5]

- Sometimes, you can even get a false positive pregnancy result, because of the recording mistake. This may be because taking pregnancy tests is too early or too late. In addition to this, some women also may misread the lines on the test kit. 

- Fertility medications sometimes have hCG levels, which can sometimes give a false pregnancy test result.[6]

-  Miscarriage can also be a possible cause of false positive, as the levels of hCG still remain high in the bloodstream even though a woman could have a miscarriage. 

See: Ovulation Bleeding Causes & Pregnancy

False test results after using expited pregnancy test

What to do after a false test using an expired pregnancy test?

Although most women these days use a home pregnancy test kit to know about her pregnancy, the home pregnancy test kit is never 100% reliable. Although kits from big brands may claim to be 100% reliable, they may sometimes give you a false positive or a false negative, which may be too dangerous for your health as well as the health of the fetus. 

The result of an expired pregnancy test may depend on three major factors that include:

- Quality of the test

- The amount of degraded hCG antibody present in the testing kit. This amount of hCG will determine the levels of Gonadotropin hormone in the urine. Thus, more HCG antibodies present in the testing kit, even after expiration, may sometimes give you a true result.

- The presence or absence of pregnancy

Thus, before being sure about the pregnancy, it is always advisable to consult your doctor. Not all home pregnancy test results are reliable, and even if you have a positive result, you must try to get the result checked by a qualified health expert.

See: Are you Pregnant- Follow this Simple Pregnancy Diet Plan

Choose the right home pregnancy test

How to choose the home pregnancy test?

Home pregnancy tests are a boon to millions of women all around the globe. The test kit not only provided you with happy news, but it also helps you to know about unwanted pregnancy. But, to be sure about your pregnancy, it is always advisable to choose a branded or a good quality pregnancy test kit. Even though you have purchased a branded testing kit, you must check the expiration date of the kit. If you have a false negative and believe you are pregnant, wait for a few days and then try the test again. 

See: Anxiety & stress in pregnancy natural remedies

Summary

Getting pregnant is not an easy task, and getting a positive pregnancy test is also never an easy task. Thus, it is always advisable to have a proper understanding of the expiration of the testing kit, and in case you are worried about the expired pregnancy test, get it rechecked by your doctor. Have a happy and healthy pregnancy!

See: Acupuncture for Nausea & Vomiting Treatment

References

1. Givner, Morris Lincoln, and Guenther Schilling. "Pregnancy test device." U.S. Patent No. 4,033,723. 5 Jul. 1977.

2. O'Connor, John F., Galina I. Kovalevskaya, and Steven Birken. "Diagnostic kit for predicting pregnancy outcome." U.S. Patent No. 7,399,636. 15 Jul. 2008.

3. Corti, Angelo, et al. "Device and method for pregnancy detection." U.S. Patent No. 5,145,789. 8 Sep. 1992.

4. Braunstein, Glenn D. "The long gestation of the modern home pregnancy test." Clinical chemistry 60.1 (2014): 18-21.

5. Barnhart, Kurt T. "Ectopic pregnancy." New England Journal of Medicine 361.4 (2009): 379-387

6. HOGAN, WILLIAM J., and J. WAIDE PRICE. "Proteinuria as a cause of false-positive results in pregnancy tests." Obstetrics & Gynecology 29.4 (1967): 585-589. 

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