Everything There Is to Know About Pregnancy Tests

Have you missed a period or noticed any other signs of pregnancy? Then perhaps you’re wondering whether to take a pregnancy test! Learn all about when to take a test, how pregnancy tests work and how accurate they are, plus how soon you can take a pregnancy test, how to read one and more.

Pregnancy Tests: How Do They Work?

Pregnancy tests work by detecting a hormone known as hCG (human chorionic gonadotropin). Often called the “pregnancy hormone,” hCG is produced by the developing placenta after a fertilized egg implants in the uterus lining following conception.

Your body will continue to produce hCG at very high levels in the first three to four months of pregnancy. It signals your body to sustain the pregnancy and can be detected by pregnancy tests in your urine and blood.


What Types of Pregnancy Tests Are There?

Two types of pregnancy tests can detect the presence of hCG: urine tests and blood tests. The typical home pregnancy test you can get at the drugstore uses a stick with a chemical strip with your urine, whereas a healthcare provider must conduct a blood test.

A Urine Pregnancy Test

A home pregnancy test uses your urine to detect hCG. If you’re wondering where to buy pregnancy tests like these, you can get one at any drugstore, grocery store or community clinic, or from your healthcare provider. Once you have one, your next question might be how to take a pregnancy test. The process for taking a home pregnancy test is relatively straightforward; here’s what to do:

  1. Read the instructions. Different home pregnancy testbrands may have slightly different directions. For example, how long to pee or how long to wait for results may vary from brand to brand.

  2. Remove the stick and cup from the packaging. What does a pregnancy test look like? Home pregnancy tests come in stick form with a strip at the end. With some, you’ll pee directly onto the end of the stick/strip, whereas with others, you’ll dip the stick/strip into a small cup of your urine.

  3. Pee. Depending on the instructions, you’ll pee directly on the stick—a prepared chemical strip—or dip it into a urine cup.

  4. Wait. All home pregnancy tests work by detecting hCG in your urine, but the instructions and wait times will vary among brands. Some brands are more sensitive than others.

  5. Read the results. Classic tests reveal the news with signs and lines. A plus sign or two lines usually indicates a positive pregnancy test. Digital pregnancy tests spell out the news with words like “pregnant” if positive or “not pregnant” if negative.

You can take a urine pregnancy test in your healthcare provider’s office or at home. In the office setting, the provider can ensure a correctly performed and give you the results.


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A Pregnancy Blood Test

Only a healthcare provider or clinician can perform a pregnancy blood test. A blood test won’t offer an immediate result like with a urine test—it can take from a few hours to more than a day—but it’s more sensitive and accurate.

A common question is how soon or how early you can take a pregnancy test. One perk about pregnancy blood tests is that they work during early pregnancy. So, how soon will a pregnancy blood test read positive or negative after conception? They work as early as 9 to 12 days after conceiving!

There are two types of pregnancy blood tests:

  • Quantitative blood test. Also known as a beta hCG test, this test measures the exact amount of hCG in your blood.

  • Qualitative test. This test indicates if the hormone is present in the blood or not.

What pregnancy test is the most accurate? Both types of pregnancy blood tests can indicate pregnancy early and more accurately than at-home urine tests.

Are Pregnancy Tests Accurate?

Most home pregnancy tests claim to have an accuracy rate of 99 percent; however, the result you receive can depend on various factors, such as:

  • When you take the test. When is the best time to take a pregnancy test? The best time to take a pregnancy test is first thing in the morning when hCG levels are more concentrated. It’s also a good idea to wait until one week after your missed period before testing, when a home pregnancy test is most accurate.

  • The expiration date of your test. Do pregnancy tests expire? Yes, they do! Make sure your test is not past its expiration date, as this can affect the accuracy of the results.

  • Your fluid intake. Did you know that drinking too much water before taking the test can dilute the hCG levels in your urine? That’s another reason why it’s best to take a test upon waking up and before drinking any fluids.

  • How you perform the test. It’s important to follow the test instructions precisely, as this can also affect the results you get.

  • The brand of the test. Some brands will be more sensitive than others.

  • If you’re taking medications with hCG in them. Although most medications won’t affect a home pregnancy test, taking fertility drugs with hCG can impact your results.

Can You Get a False Negative Result?

Yes, it’s possible to get a false negative result on your pregnancy test when you’re actually pregnant. What can cause a false negative pregnancy test? False negatives typically occur if

  • you take the test too soon (before one week after your missed period)

  • your urine is too diluted from drinking liquids

  • you don’t wait long enough for the results.

So, how soon will a pregnancy test read positive or negative? Depending on the test and its instructions, you may need to wait as long as 10 minutes to get the most accurate result. Follow the instructions on your test closely and give the test time to work. If you’re feeling anxious or excited, you may even want to set a timer and find a distraction, so you don’t look too soon!

Can You Get a False Positive Result?

It’s possible to get a false positive result on a home pregnancy test, meaning that the test shows you’re pregnant when you’re not. This outcome is rare, however. What can cause a false positive pregnancy test? You could get this result if you’re taking a fertility drug containing hCG, for example, or if you simply take the test incorrectly.

When Should You Take a Pregnancy Test?

We’ve already mentioned the best time to take a pregnancy test above, but this is such a common question that it’s worth emphasizing! For a typical 28-day cycle, the best time to test for pregnancyis a week after your missed period, when you can expect more accurate results. After your first missed period is when your body will likely be producing enough hCG.

But can you take a pregnancy test while on your period? How long after sex can you take a pregnancy test? Again, these are very common questions, but remember that your body only produces hCG after the fertilized egg implants itself in the lining of your uterus and the placenta starts to form, which might cause some light implantation bleeding. Your hCG levels will double every two to three days during the first few weeks of pregnancy, which is why it’s a good idea to wait to take a pregnancy test.

In the meantime, if you’re wondering whether you’re pregnant or not, you might want to look out for some early signs of pregnancy, which may include

What to Do After a Positive Pregnancy Test

Once you learn the news, make an appointment with your healthcare provider. If you want to know how far along you are in your pregnancy, check out our Due Date Calculator.


For the most accurate results, the best time to take a pregnancy test is one week after your first missed period. This is when levels of hCG (the pregnancy hormone) can be detected, so your test will be more accurate.

The Bottom Line

If you’ve been trying to conceive, missed your period or started to notice some of those typical pregnancy symptoms, you probably want to know whether you’re pregnant. Home pregnancy tests, which work by detecting levels of hCG in your urine, are a great way to confirm that you're pregnant. For the most accurate results, it’s best to wait at least a week after your first missed period or opt for a pregnancy blood test by your healthcare provider, which can detect pregnancy earlier.

There’s a lot of fascinating science that goes into pregnancy tests, but we hope this basic guide helps you understand how at-home urine tests or blood tests work, when you should take one and how accurate they are.

If you received a positive result and are now starting to prepare for a new baby, don’t forget that the Pampers Club app rewards you for all those diapers and wipes purchases!

How We Wrote This Article The information in this article is based on the expert advice found in trusted medical and government sources, such as the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists. You can find a full list of sources used for this article below. The content on this page should not replace professional medical advice. Always consult medical professionals for full diagnosis and treatment.