How Do Pregnancy Tests Work? Are They Accurate?

If you have recently missed your period, a pregnancy test is the first step to figuring out whether you’re pregnant.

In today’s blog, we’ll explore the different types of pregnancy tests, how they work, and how accurate they are. Keep reading to learn more.

What Are The Different Types of Pregnancy Tests? 

There are two different types of pregnancy tests: urine tests and blood tests. You can purchase urine tests at drug stores or grocery stores and perform them at home. A doctor’s office or a pregnancy care center can also perform urine pregnancy tests. You do not need a prescription to purchase a pregnancy test.

Blood tests are only performed at doctor’s offices. Blood tests are only used for special circumstances, such as when the healthcare provider suspects there could be an issue with the pregnancy or if the patient is undergoing fertility treatments.

Unless there are special circumstances or complications, blood tests are rarely used to detect pregnancy, since urine tests are cheaper and usually yield the same results.

How Do Pregnancy Tests Work? 

Pregnancy tests check for a hormone called HCG, or human chorionic gonadotropin. You can find this hormone in urine or blood, and it only appears when you are pregnant. 

Once you become pregnant, the HCG hormone starts building up in your urine/blood, doubling every 2 to 3 days.[1] However, it takes several days after conception for HCG levels to rise to a point where they can be detected by a pregnancy test. For example, if you have a 28 day menstrual cycle, you can detect hCG in your urine 12-15 days after ovulation.[2]

How Accurate Are Pregnancy Tests? 

Most pregnancy test brands claim to be 99% accurate when used correctly.[3] The words “when used correctly” are key! Many people make the mistake of testing too early, before the HCG levels rise to a point where they can be detected by a pregnancy test.[4]

When this happens, they may get a “false negative.” This means the test result is negative, but they are actually pregnant. False negative results can happen often. This is especially true if the pregnancy test is done before a missed period. It can also happen if the woman has a history of irregular periods. 

Healthcare providers suggest waiting until at least one day after a missed period to take a pregnancy test for the most accurate results. If you receive a negative result but still think you may be pregnant, wait a few days and try again.

Can I Interpret The Results of A Pregnancy Test On My Own? 

Every home pregnancy test brand gives clear and easy instructions on how to interpret the results of the test. Usually, doing so on your own is easy; however, there are cases where a faint line appears. This could make it difficult to tell whether the result is positive or negative.

In this case, reach out to Life Choice Pregnancy Care Center for help. We have registered nurses on staff that can help interpret the result of your pregnancy test and advise you on what to do next.

Do I Need An Ultrasound To Know If I am Pregnant? 

Pregnancy tests are usually enough to determine whether or not you are pregnant. However, you do need an ultrasound to determine whether your pregnancy is viable and how far along you are. You need this information as you consider your pregnancy options. 

If you are thinking about having an abortion, it is crucial to receive an ultrasound first. This applies to both chemical abortion (also known as the abortion pill or Plan C) and surgical abortion. Taking the abortion pill without knowing how far along you are in your pregnancy can lead to excessive bleeding, failed abortion, and other serious health complications. 

Life Choice Pregnancy Care Center offers free ultrasounds to eligible patients. Call us today to see if you qualify for a free ultrasound at 270-717-5433. 

Please be aware that Life Choice Pregnancy Care Center does not provide or refer for abortion services. 

Sources

1. Mayo Foundation for Medical Education and Research. (2022, December 23). Home pregnancy tests: Can you trust the results?. Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/getting-pregnant/in-depth/home-pregnancy-tests/art-20047940   
2. Center for Devices and Radiological Health. (n.d.). Pregnancy. U.S. Food and Drug Administration. https://www.fda.gov/medical-devices/home-use-tests/pregnancy  
3. Cleveland Clinic. (2024, September 9). Pregnancy test: When to take, Types & Accuracy. https://my.clevelandclinic.org/health/diagnostics/9703-pregnancy-tests 
4. See sources #1 and #3.