A pregnancy test can tell whether you’re pregnant or not by detection of human chorionic gonadotropin (hCG) hormone in urine or blood.
High levels of hCG are a sign of pregnancy. hCG increases quickly in the first ten weeks after a fertilized egg attaches to the inside wall of the uterus.
Urine tests for pregnancy are most accurate when you do the test a week or two after you’ve missed your menstrual period. If you take a urine test too close to the time you got pregnant, the test could say that you are not pregnant even when you really are. That’s because your body may not yet have made enough hCG to show up on the test.
You can have an hCG urine test at your health care provider’s office or you can do the test yourself with an at-home test kit. These tests are basically the same, so many people use a home pregnancy test before calling their provider. If you follow the instructions carefully, home pregnancy tests are about 97-99% accurate. They can give you the results in minutes.
Blood tests for pregnancy can be done at your provider’s office or a lab. These tests can find very small amounts of hCG, so they can accurately show whether you’re pregnant before you’ve missed your period. But hCG blood tests aren’t commonly used to check for pregnancy.
That’s because urine tests are less expensive, very accurate, and provide quicker results than blood tests. hCG blood test results may take hours to more than a day.
Other names: human chorionic gonadotropin test, HCG test, qualitative hCG blood test, quantitative hCG blood test, Beta-hCG urine test, total chorionic gonadotropin, hCG total OB
What is it used for?
A pregnancy test is used to find out whether you’re pregnant.
Why do I need a pregnancy test?
You may need this test if you think you’re pregnant. Symptoms of pregnancy vary from person to person. The most common sign of early pregnancy is a missed period. Other common signs of early pregnancy may include:
Swollen, tender breasts
Frequent need to urinate (pee)
Nausea and vomiting (also called morning sickness)
Feeling bloated or swollen in your abdomen (belly) or body
If you need to have medical treatment that could harm an unborn baby, you may also need a pregnancy test to make sure that you aren’t pregnant.
What happens during a pregnancy test?
Home pregnancy tests are quick and easy to use. You can buy a home pregnancy test kit without a prescription. The kits include test sticks or strips that react to hCG in your urine. The steps for doing a test depend on the brand, so it’s very important to follow the instructions that come with your test.
For most test kits, you’ll either:
Hold the test stick or strip in your urine stream
Collect your urine in a cup and dip the test stick or strip into the cup
After waiting a certain number of minutes, you’ll check your results on the test stick or strip.
The instructions will tell you what to look for. In general, to get the most accurate results with any home pregnancy test, you’ll need to:
Check the expiration date before you use the test.
Test your first morning urine. Morning urine usually has more hCG than urine later in the day.
Use a timer. If you guess the timing, your results may not be accurate.
Blood tests are done at your provider’s office or a lab. A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This process usually takes less than five minutes.
Will I need to do anything to prepare for the test?
If you’re doing a urine test, don’t drink large amounts of fluid before collecting your sample. That could dilute the hCG in your urine, and it may not show up on the test.
Otherwise, you don’t need any special preparations for a pregnancy test that uses urine or blood.
What do the results means?
Your results will show whether you’re pregnant.
A negative result means hCG wasn’t found in your sample, so you may not be pregnant. But a negative result doesn’t always mean you’re not pregnant. If you did a home urine test too soon, your body may not have made enough hCG to show up the test.
hCG levels increase every day during early pregnancy, so it’s a good idea to repeat the test again in a week.
If you get negative (not pregnant) results on two home tests, but you still think you’re pregnant, call your provider. If you get a negative result on a test that your provider does, ask your provider if you need another test.
A positive result means that hCG was found in your sample. That usually means that you’re pregnant. It’s important to see your provider as soon as possible to make sure you get the right care.
If you did a home test, your provider may do another test to confirm your pregnancy.
If you’re taking medicine to help you get pregnant (fertility drugs), your test results may show that you’re pregnant when you’re not. Your provider can check to see whether you’re really pregnant.
Is there anything else I need to know about a pregnancy test?
Most pregnancy tests simply measure whether or not you have hCG in your sample. But certain pregnancy tests also measure how much hCG you have. These tests are called quantitative hCG tests, and they’re usually done on blood samples.
The amount of hCG in your body can give your provider important information about your pregnancy and the health of your unborn baby.
Quantitative hCG tests are sometimes used to help:
Find out the age of the fetus if you’re very early in your pregnancy
Monitor your pregnancy if you have a high risk of miscarriage
Check for certain problems, such as:
Ectopic pregnancy, which is a fertilized egg that tries to grow outside of the uterus. The egg cannot grow into a baby when it’s in the wrong place. It must be removed to avoid damage to your organs. This can be a medical emergency.
Molar pregnancy (hydatidiform mole), which is an abnormal growth of tissue in the uterus. It’s caused by a fertilized egg with such severe genetic problems that it cannot become a baby. The growth can turn into cancer and must be removed.
Problems in the unborn baby, including Down syndrome, other chromosome problems, and certain birth defects (hCG testing is usually part of a group of prenatal screening tests called a “triple” or “quadruple” screen test.)
Your provider may also order a quantitative hCG blood test to help diagnose or monitor health conditions that aren’t related to pregnancy. These include ovarian and testicular cancer along with other conditions that can increase hCG levels.