Do Pregnancy Tests Always Show Accurate Results?

Pregnancy tests
Photo by Nataliya Vaitkevich

Do Pregnancy Tests Always Show Accurate Results?

It’s been a few days since your expected period and now, you’re wondering if you’ve gotten yourself pregnant. Depending on your circumstances, this could either be really good news or a piece of extremely bad news. No matter which camp you are on, you can save yourself from stressing all about this issue by simply doing a pregnancy test. You are waiting for a baby, but your test gives negative results. Maybe vice versa, despite that you were always very careful; your test shows positive results. Can you really trust pregnancy test results?

Trying one out for the first time can be quite confusing depending on what type of pregnancy test kit you have. Besides, there are ways to increase the accuracy of home pregnancy tests that you probably don’t know. Hence, we’ve made this article to inform you all about pregnancy tests and how they work.

How do pregnancy tests work?

Pregnancy tests

Although there are different kinds of pregnancy tests out there, all of them work on the same principle. It works by detecting a certain hormone called human chorionic gonadotropin (HCG) in your urine or blood which is produced in high amount when you are pregnant or have certain illnesses.

This hormone is produced by your placenta and will rapidly increase in amount once your fertilized egg begins to attach itself to the walls of your uterus. However, even if you are not pregnant, your body will still produce HCG albeit in very little amounts. That is why pregnancy tests will only register a positive when your HCG level reaches the minimum threshold of that particular pregnancy test.

Typically, you will have a negative result if the HCG level in your urine or blood is only at or less than 5 mlU/ml (milli-international units per milliliter). On the other hand, you will have a positive test result if the level of your HCG reaches 25 mlU/ml at the very least. When you are pregnant the level of HCG will double every 72 hours.

Hence, it is very important to understand the right timing of when you should take a pregnancy test to prevent cases of false positives and false negatives.

Pregnancy test accuracy

All home pregnancy tests available in drugstores are urine-based and help to detect early pregnancy. As stated above, taking a pregnancy test heavily relies on correct timing for a very accurate result. According to available data, a pregnancy test is accurate 99 out of 100 times if you follow all the methods and procedures correctly.

It does not matter whether you are only using a pregnancy test kit you brought from a  drugstore or if you take your pregnancy test in a doctor’s office. It will be extremely accurate as long as you do not take it too early or too late. Besides, any kind of pregnancy tests includes instructions that you must follow, so always read the instructions before testing.

Hence, if you are not too confident with using a home pregnancy test kit correctly, you can always seek out your local midwife or your doctor for advice. You can even book an appointment if you would prefer to have your blood taken for a pregnancy test.

False-positive and false-negative results

Pregnancy tests

In the scientific field, there is no such thing as an absolute. Even if you have done your pregnancy test correctly and at the right timing, it is not a guarantee that your result will be absolutely correct. That’s why a pregnancy test is only 99% effective since there is a 1% chance that it will give out an inaccurate result.

Some conditions could increase HCG levels without resulting in pregnancy such as certain types of cancer, inflammatory bowel disease, trophoblastic disease, and a laboratory or test kit error. All of these conditions could cause a pregnancy test to return a false-positive result. Furthermore, abortion or miscarriage that you have experienced recently can be another reason for false positive result. Taking medications including HCG as an active ingredient to treat infertility may also lead to the same result.

False results are very rare, but still sometimes happen. As for false-negative results, this usually happens when you’ve done the test too early. At early pregnancy HCG levels are low, therefore you may get negative result even if you are actually pregnant. Many tests say that they work a few days before a missed period, but you may get less accurate result. If you worry about missing period and a negative test result, repeat the test after 3-4 days. If it’s still negative, probably something is happening in your body and you need gynecologist’s consultation.


How to increase the accuracy of home pregnancy tests?

Cheap home pregnancy tests might look unreliable as opposed to a laboratory test conducted by a doctor. But as stated above, they practically have the same accuracy if certain conditions are met and followed.

1. To increase the accuracy of a home pregnancy test, you should make sure that you only take it at least after 2 weeks of your missed period. This is because a fertilized egg would take 1 to 2 weeks on average before it could implant itself to your uterine wall, thereby prompting the increased production of HCG.

2. Better do testing in the morning when HCG is more concentrated in your urine. This will help to increase the accuracy of result.

3. Don’t drink much water before testing. Because much amount of liquid dilutes the HCG in urine and that may lead to false negative result.

4. You could also take several tests using different pregnancy test kit brands at different periods. Take one during the morning and one during the evening then repeat it the next days to ensure your results.

If you still doubt the accuracy of your home pregnancy test results, you could always call your doctor and have it done in a laboratory instead.


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Irregular periods. Main reasons and treatment 

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How to get ready for pregnancy


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