Should You Use an Expired Pregnancy Test?
Many of us have been there, right? Waiting for a period that just won’t show up when expected or, on the contrary, hoping it doesn’t show up for the next nine months. But then, there’re home pregnancy tests that you can use and the results will probably put you out of doubt.
If you’ve got some pregnancy test strips or a test kit lying somewhere in your drawer or closet, you want to make sure they’re not expired before using them.
Whether you’re trying to get pregnant or not, you should not consider using an expired pregnancy test because you don’t want to have a false positive or negative result.
How Do Pregnancy Tests Work?
First, it is important to understand how pregnancy tests work to know why it isn’t a good idea to use an expired test to confirm or exclude pregnancy.
Home pregnancy tests work by detecting a hormone in urine known as human chorionic gonadotropin (hCG).
A protein in the test kit–also known as a monoclonal antibody–reacts with the hCG in your urine and causes a chemical reaction, resulting in color change if you are pregnant, i.e., if your urine hCG level is greater than 25 mlU/mL (detection thresholds vary between brands, ranging between 10 mIU/mL and 100 mIU/mL).
You can have a positive test result if you perform the test several days after conception or one day after a missed period. Some early-result pregnancy tests can detect pregnancy hormone levels six days before a missed period.
The immunoassay strips included in pregnancy test kits are composed of fibres and coated with a monoclonal antibody. So, like many products, home pregnancy tests have an expiry date, which is usually displayed on the product box or packaging.
When Do Pregnancy Tests Expire?
Most pregnancy test kits have a shelf life of two to three years after production. In general, cheaper brands have a shorter shelf life of about two years after the date of production. The more expensive ones, such as ClearBlue pregnancy tests, expire three years after the manufacture date.
Expiry dates are, in most cases, displayed as follows: Month Year. Often times, women have asked whether it is safe to use a pregnancy test one, three, or six months after its expiry date. The simple answer is “NO”.
If the expiry date on your pregnancy test kit is July 2017, for example, and today is July 15, 2017, do not use the test.
- Don't use a test kit if it has reached the month of expiry, whether it is an early or standard pregnancy test.
How Accurate Are Expired Pregnancy Tests?
As a member of many forums for mothers and future mothers, I’ve read posts where women affirmed they’d never had a problem using expired pregnancy tests.
I’ve also come across posts where the user used expired pregnancy tests and got a negative result on the first attempt and a positive one on another (with both tests performed on the same day).
While there’s no evidence that a pregnancy test might be accurate a few weeks to months after expiration, the results reported by women in forums and other social media platforms are inconsistent, suggesting that you should not rely on the results obtained from expired kits or strips.
What Outcome Should You Expect When You Use an Expired pregnancy Test?
If after reading this post, you still feel like you want to use that expired test kit, consider the following outcomes:
- The test strips (i.e., if you perform more than one test) show completely different results.
- The result is negative although you’re pregnant. There’re two possibilities in this case: (1) Your hCG level is still too low to be picked up by a test kit, even a properly functioning one. Maybe you tested too early? (2) The reagent in your test strip/ kit has expired and can therefore not pick up hCG in your urine.
- The result is positive although you’re not pregnant. When exposed to certain environmental conditions such as humidity or heat, an expired pregnancy test can give a false positive result. You should consider this if you stored your test kits in a bathroom cabinet.
- The result is positive and you’re indeed pregnant.
- The result is negative and you’re not pregnant.
Thinking of it, why risk getting a false result with an expired test when you can purchase one of the many affordable brands for less than $20 and get a properly-functioning test?
What Should You Do after Using an Expired Pregnancy Test?
In the first scenario, let’s say your result is negative. When did you perform the test? Was it before your missed period? If yes, you should perform another test on the day or a few days after your missed period.
BUT buy a new test to avoid a false negative result. Also, watch out for other symptoms of pregnancy, which some women may experience as early as one week after conception.
In the second scenario, your result is positive. You should ask yourself these questions:
1. Are you experiencing symptoms of pregnancy?
Here are some common early symptoms that you may confuse with those that you might experience before a few days before or during menstruation:
- Nausea and / or vomiting
- Food aversions or cravings
- Tender, swollen breasts
- Increased urination
- Spotting and cramping
2. Are you taking a drug that might affect your pregnancy test results?
If you take a drug containing hCG, you can get a false positive pregnancy test. After the drug is injected, it takes approximately one to two weeks for the drug to be cleared from your body; the time it takes for your body to excrete the drug depends on the dosage that you received.
Therefore, if you are undergoing treatment for fertility and are taking injections of hCG, it is advisable that you wait for at least two weeks after the last injection before attempting a pregnancy test.
Apart from drugs containing hCG (Novarel, Ovidrel, Pregnyl, and Profasi), the following have been found to cause a false positive pregnancy test:
- Anti-anxiety medications, such as diazepam (Valium) or alprazolam (Xanax)
- Antipsychotic medications, such as clozapine or chlorpromazine
- Anticonvulsants, such as phenobarbital or other barbiturates
- Diuretics, such as furosmide (Lasix)
- Methadone (sold as Dolophine)
- Medications prescribed for Parkinson’s disease, such as bromocriptine (Parlodel)
- Antihistamines, including promethazine
3. Have you experienced spotting or mild bleeding recently?
If yes, you should consider visiting a health care professional so that they can perform a more reliable test to confirm or exclude a pregnancy.
Note an ectopic pregnancy (a situation where the fertilized egg implants somewhere other than the uterine lining, such as the fallopian tube or ovary) can also cause a false pregnancy test.
An ectopic pregnancy is not viable and can be life-threatening if not treated. Therefore, it is important that you visit the nearest emergency unit if you are experiencing severe abdominal cramps or heavy bleeding.
If you had an early miscarriage, it might take several weeks for your hCG levels to return to non-pregnancy levels. Therefore, you might have a false positive reading if you took a pregnancy test after an early miscarriage due to the presence of hCG in your urine.
Home pregnancy tests are an easy and reliable way to determine whether you’re pregnant. However, to avoid getting false results, you should use a pregnancy test well before its expiry date.
Have you ever used an expired pregnancy test? What was your experience? Are you considering using an ovulation test as an alternative to a pregnancy test? You might want to read this post before trying that.