All About Pregnancy Tests

Have you missed a period, or noticed any other signs of pregnancy? Then you may be wondering whether or not you should take a pregnancy test. Learn all about how tests work, the types available, and how accurate they are. We're here to answer your questions about pregnancy tests, so read on to learn more!

How Do Pregnancy Tests Work?

Pregnancy tests work by detecting a pregnancy hormone known as hCG, human chorionic gonadotropin, which is produced in the developing placenta after the fertilized egg implants in the uterus lining in the first few days following conception. It will continue to be produced at very high levels in the first three to four months of pregnancy. This hormone signals your body to sustain pregnancy and can be detected in your urine and blood.

What Types of Pregnancy Tests Are There?

The presence of hCG can be detected with:

  • A urine test. This test detects whether there is hCG present in your urine. You can take the test by peeing directly onto the "stick" — a prepared chemical strip — or by using a urine cup. 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 and you'll find a range of urine pregnancy tests on the market, from the classic tests that tell you the good news with a plus sign or that extra line to digital pregnancy tests that spell out you're pregnant in words. You can also do a urine test in the doctor's office, which has the advantage over home tests in that your doctor can inform you about the result and instruct you how to use the test properly.

  • A pregnancy blood test. You can only get this type of test at the doctor's office, and it's not carried out as a routine measure, as blood tests can be expensive. A blood test won't give you an immediate result as you would get with a urine test — it can take a few hours to more than a day — but it is more sensitive and can also detect a pregnancy as early as 9 to 12 days after conception. There are two types of pregnancy blood tests: a quantitative blood test or beta hCG test, which measures the exact amount of hCG in your blood, and a qualitative hCG blood test, which indicates if the hormone is present in the blood or not.

How Accurate Is a Home Pregnancy Test?

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. For a more accurate result, take the test one week after your missed period and first thing in the morning, when hCG levels are more concentrated.

  • The expiration date of your test. Make sure your test is not past its expiration date, as this can affect the accuracy of the results.

  • Your fluid intake. Drinking too much water before taking the test can dilute the hCG levels in your urine, making it harder for the test to detect the presence of this pregnancy hormone.

  • How you perform the test. It's important to follow the instructions of the test 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, if you're taking fertility drugs with hCG, this can affect your results.

Can I Get a False Negative Result?

Yes, it is possible to get a negative result on your pregnancy test when you are actually pregnant. This is called a false negative. You may get a false negative if you take the test too early, if your urine is too diluted, or if you don't wait long enough for the results. 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. You may even want to set a timer, so you don't take the reading too soon.

Can I Get a False Positive Result?

It is possible to get a false positive result on a home pregnancy test, in which case, the test shows you're pregnant when you're not. This outcome is rare, as your body won't produce hCG when you're not pregnant. However, you may get a positive result when you're not pregnant if you're on a fertility drug containing hCG.

When Should I Take a Pregnancy Test?

The best time to take a pregnancy test is a week after your missed period. You can take a test earlier, but you may not be producing enough hCG for the test to detect if you test too soon. Your body only produces hCG after the fertilized egg implants itself in the lining of your uterus, and the placenta starts to form. During early pregnancy, your hCG levels will double every two to three days, which is why it's a good idea to wait with the test. In the meantime, if you are wondering whether you're pregnant or not, you may want to look out for some early signs of pregnancy, which may include

  • tender, swollen breasts

  • frequent urination

  • morning sickness, which despite its name, is nausea (with or without vomiting) that can occur any time of day

  • fatigue.

Where Can I Get a Pregnancy Test?

You can buy home pregnancy tests at a drugstore, grocery store, and at some convenience stores.

However, you can also go to your healthcare provider, community clinic, or Planned Parenthood health center for a test.

What Do I Need to Do If the Pregnancy Test Is Positive?

Once you learn the good news, make an appointment with your healthcare provider to find out more about your pregnancy.

Congratulations! We're really excited for you.

If you want to know how far along you are during your pregnancy, you can check out our Due Date Calculator.

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