Blood Pregnancy Tests

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Blood tests can confirm pregnancy by checking for the presence of the hormone, human chorionic gonadotropin (hCG). These tests are more sensitive than urine tests and can detect a pregnancy earlier. Blood pregnancy tests yield a positive result if they detect 1 to 2 mIU/mL (milli-international units per milliliter), while urine tests require hCG levels to reach 20 to 50 mIU/mLs.

Reasons for a Blood Pregnancy Test

Blood pregnancy tests are more sensitive than urine tests. They are typically reserved for those struggling with infertility or a suspected miscarriage.

A blood test can confirm pregnancy as early as nine days after conception. Urine pregnancy tests will take at least 10 days or longer.

Blood pregnancy tests have to be taken at the doctor's office. Your doctor might advise you to wait until a missed period to do any type of pregnancy testing so you can get the most accurate result. Testing too early can produce a false negative. Unlike home pregnancy tests, you'll have to wait for a blood pregnancy test result to come back from the lab.

Qualitative vs. Quantitative Testing

There are two types of blood pregnancy tests:

  • Qualitative blood serum test: This will confirm whether or not hCG is present, basically offering a yes (you're pregnant) or a no (you're not pregnant) result. The qualitative hCG blood test is about as accurate as a home urine test.
  • Quantitative blood serum test: This test is also known as the beta hCG test, measuring the exact amount of hCG in your blood. Because this test can detect even trace amounts of hCG, it is highly accurate. Doctors use this test, along with ultrasound, to diagnose an early pregnancy loss.

False Negatives or Positives

A urine pregnancy test is just as accurate as a blood test (99%), as long as you wait the recommended amount of time to take it. HCG doubles every couple of days in the very early stages of pregnancy. Urine tests can produce a false negative if the urine is diluted (from over-hydration) or the test is taken too early.

As with urine/home pregnancy tests, it is possible to end up with false results (both negative and positive) from a blood pregnancy test.

A false negative (test is negative, but you're pregnant) can occur if the blood pregnancy test was performed too early. There may not be enough hCG in the blood to detect a pregnancy. If you believe that you received a false negative from testing too soon, your doctor may repeat the test after 48 to 72 hours.

Beyond testing too early, a false negative blood test can occur if there is a condition called gestational trophoblastic disease. In this case, the lab will need to dilute the sample before performing the test to get an accurate result.

False positives (test is positive, but you're not pregnant) very rarely happen. You may get a false positive if you are taking a medication that contains hCG (such as when undergoing fertility treatments) or due to certain medical issues. Possible causes of a false positive may include:

  • Antibodies present in the blood due from exposure to certain animal products (called heterophile antibodies)
  • Blood or plasma transfusion
  • If you took hCG for weight loss, doping, or fertility
  • IgA deficiency
  • Renal failure
  • Rheumatoid factors
  • Some types of cancer

Disadvantages of Blood Pregnancy Tests

Even though a blood pregnancy test can be performed earlier, it can take longer to receive your results compared to a urine test. Timing of results vary from lab to lab and can range from an hour to a few days.

Blood pregnancy tests must be performed in your doctor's office, taking more time out of your schedule. Blood tests are more expensive than home pregnancy tests (depending on doctor and lab fees). Waiting a few extra days to do a home urine test is more convenient.

Possible Risks

There is very little risk associated with getting a blood pregnancy test. Just as with any blood test, you may feel lightheaded, faint, have excessive bleeding, infection or bruising at the puncture site, and/or hematoma (blood accumulating under the skin).

Since veins and arteries differ in size from one person to another (and from one side of the body to the other), getting a blood sample could be more difficult for some people. In order to get the required blood sample, you might need multiple pricks to locate a vein.

A Word From Verywell

Waiting to find out whether or not you're pregnant can feel like it takes an eternity, especially when you're anxious to get the results. It's best to take your doctor's advice and avoid testing too soon. Home urine tests or in-office blood testing can give you false information when not performed as directed. If you have concerns or suspect a false negative or positive, talk to your doctor about further testing to confirm your results.

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5 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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