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These days it is quite easy to ascertain a pregnancy without having to go to the doctor and sit through a barrage of invasive procedures. Home pregnancy tests have made the process both private and easy. They work on the principle of hormone quantification: the test strips come laced with a certain molecule which can detect the presence of human chorionic gonadotropin or hCG in the urine. As the levels of this hormone increase above a certain threshold, it can be detected using one of these tests.
However, while these tests are user-friendly, they can have some problems. For instance, one of the most common issues with pregnancy tests is their expiration date. This article will help you understand all about expired pregnancy tests, their accuracy and answers some important questions you may have.
Do Pregnancy Tests Really Expire?
A lot of pregnant women don’t even realise the fact that pregnancy tests, like all other perishable goods, have an expiration date. Nevertheless, home pregnancy tests certainly have a best before date, which is often mentioned on the container or the external packaging. So if you have been attempting to get pregnant for some time, but have been experiencing a negative pregnancy test, it might imply that the test itself is non-functional.
Why Do They Expire?
As already mentioned, pregnancy tests contain a chemical which can detect the levels of hCG in the urine. This chemical is known as an hCG antibody, and it consists of two arms which identify and bind to the hCG in the urine. However, after a certain point, the antibody arms degrade and break down, making them invalid. This is the most common reason behind the expiration of pregnancy tests.
When Does a Pregnancy Test Expire?
This depends on the brand of the pregnancy tests, but the general shelf life ranges from two to three years starting from the manufacturing date. The cheaper tests expire faster than the more expensive ones. In fact, often expensive tests can be viable even after the expiration date, but on the other hand, cheaper ones may expire before the set date due to the low quality of production. In either case, it is the safest bet to only use pregnancy tests at least a few months before their expiry date.
Does an Expired Pregnancy Test Kit Still Work?
An expired pregnancy test kit might technically work in rare instances, but the result will be what is known as a false positive. An expired test positive result basically means that the test will claim you are pregnant when you are actually not.
The immediate next question you might have is: can an expired pregnancy test give a false negative? The answer is, yes: expired tests are also less likely to be sensitive enough to detect hCG hormone, leading to a false negative. In this case, even if you are pregnant the test will show that you are not. These results are especially common if the test has been kept in a warm and humid area for extended periods of time.
Both these situations can escalate quickly and create unnecessary problems! So, always check the expiry date of the pregnancy kit before purchasing/using it. If you happen to use an expired test kit by mistake, you don’t need to be anxious over the results of an expired test. Simply procure a new kit and get the right result.
How Accurate is an Expired Pregnancy Test?
Home pregnancy tests are said to be around 98-99% accurate if employed using the correct protocol, at least a week after the first missed period. However, near the expiry date, the accuracy drops to untrustworthy levels. Many people claim that they still obtained the expected results from expired pregnancy strips, but these results are not consistent or reliable. Further, a false negative might have you believe that you are not pregnant. In this case, you may not take the necessary safeguards that pregnant women should, such as prenatal vitamins, avoiding alcohol or cigarettes and so on. This could lead to serious health complications for your growing foetus as well as yourself.
What to Expect When You Use an Expired Pregnancy Test
As mentioned earlier, expired pregnancy tests can lead to four results: a true positive, a true negative, a false positive and a false negative. However, the false results can be due to other reasons as well.
A false positive test could be because of:
- Ectopic or non-viable pregnancy, wherein the zygote fails to implant in the uterus, but rather attaches elsewhere. If you experience bleeding and extreme lower body pain at any time during your pregnancy, please consult your doctor immediately.
- Recording mistakes while taking the test include taking it too early or too late, or misreading the lines on the test strip. Please read the guidelines that come with the pregnancy test kit beforehand.
- Fertility medications sometimes have hCG, which can give a false positive result.
- Miscarriage is a possibility for a false positive result because the levels of hCG hormone in the bloodstream remain high even weeks or months after a miscarriage.
A false negative test may be because of:
- Recording mistakes like not observing the test strip lines, using the first or last few drops of urine rather than taking the sample from the midstream.
- Urine dilution, which means the hCG levels in it will also be low. Ideally, you should use morning urine, which is considerably more concentrated.
- Not waiting long enough after your first missed period, as this could mean there has not been enough time for the hCG in your body to increase.
What if You Use an Expired Test to Detect Pregnancy
Home pregnancy kits are not complete 100% reliable, and must always be confirmed by your doctor. Especially when using expired tests, you might have variable and false results. The results of an expired pregnancy test depend on three main factors:
- The quality of the test itself, which has an important role to play in the accuracy of the expired test.
- The amount of degraded anti-hCG antibody, the chemical which is used to measure the levels of human chorionic gonadotropin, the pregnancy marker, in the urine.
- The presence or absence of the pregnancy itself.
Here are a few frequently asked questions regarding the use and efficacy of expired pregnancy test kits.
1. Can an early pregnancy test expire?
Early pregnancy tests are special tests which are considerably more sensitive. They can even identify a pregnancy up to a week before the first missed period. However, like all chemical products, early pregnancy tests too have an expiration date. They might take a bit longer to expire, but it will certainly happen. Please use a new early pregnancy test rather than one close to its expiry date.
2. Can you use an expired digital pregnancy test?
It is recommended not to use an expired pregnancy test, whether it be the regular type or the digital type. An expired test kit will never give reliable results.
3. How to choose the right pregnancy test?
The most important thing to do before choosing the pregnancy test is checking the expiration date while buying it and before using it. Further, it is possible that the pregnancy test strips could have different expiration dates, so keep an eye on them individually.
Home pregnancy tests are a boon, providing quick and accurate results. But this only applies to unexpired merchandise. There is no need to be unsure of your test results for no reason, so please only use brand new pregnancy kits only. If you have received a false negative result but you believe that you are pregnant, wait for about a week and try the test again with a brand new strip. Finally, only your doctor will be able to absolutely confirm your pregnancy, so if you have any doubts about your home test results, please consult them as soon as possible.
Also Read: Simple Homemade (DIY) Pregnancy Tests