Understanding Pregnancy Tests: Urine & Blood

Couple reviewing the results of their pregnancy test

There are two types of pregnancy tests; one uses a urine sample, the other a sample of blood. Both tests detect the presence of a hormone called human chorionic gonadotropin (hCG). This hormone is produced by the placenta shortly after the embryo attaches to the uterine lining and builds up rapidly in your body in the first few days of pregnancy. It is this rapid shift in hormones that triggers most of your pregnancy symptoms.

Urine Tests:

Urine tests can be performed in two different ways and these can be performed at home or in a clinic. One way involves collecting your urine in a cup and dipping a stick into the urine, or putting urine into a special container with an eyedropper. Another option involves placing a stick into your urine stream and catching your urine in midstream.

Tests vary in how long you have to wait to get a result. You will be looking for a change in color, a line, or a symbol (like a plus or minus). The newer digital pregnancy test offered by Clearblue Easy makes reading your results simple: the window will either show the words “not pregnant” or “pregnant”.

You can also get recommended midstream urine tests online:

All tests come with instructions, and it is important that you follow these instructions to get an accurate reading.

When can I take a urine test?

Most doctors recommend that you wait until the first day of your missed period before taking a urine pregnancy test. This is usually about two weeks after conception. However, some tests are more sensitive than others and can be taken earlier.

How accurate are urine tests?

Urine tests or home pregnancy tests are around 97% accurate when done correctly. Home pregnancy tests are great to use because they can be done at home, they are usually low in cost (anywhere from $7.99 to $19.99), private, they give a fast result, and are easy to use. However, if done incorrectly or taken too early, the result can be inaccurate. If you get a negative result and still have symptoms of pregnancy (missed period, nausea, breast tenderness and fatigue), wait a week and take another test or contact your doctor so you can have a blood test done.

Blood Tests:

There are two types of blood tests. A quantitative blood test measures the exact amount of hCG in the blood, and a qualitative hCG blood test gives a simple yes or no answer to whether you are pregnant or not.

Advantages of having a blood test done:

  • Can detect a pregnancy earlier than a urine test at about 7-12 days from possible conception (but if a negative result is received, a test should be repeated if a period is missed.)
  • Can measure the concentration of hCG hormone in your blood (this is useful information for your healthcare provider in tracking certain problems in pregnancy)

Disadvantages to having a blood test done:

  • More expensive than a urine test (price depends on cost of doctor’s visit and lab fees)
  • Takes longer to get result
  • Must be done in a doctor’s office

Frequently Asked Questions About Pregnancy Tests:

If I get a positive result on a home pregnancy test, does that mean I am pregnant?

A positive result from a home pregnancy test shows the presence of the hormone hCG in your system. When an egg is implanted in a woman’s uterine lining, hCG hormones begin to develop and multiply. This is a sign that you have become pregnant.

If I get a negative result on a home pregnancy test, does that mean I am not pregnant?

A negative result can mean that you are not pregnant, you took the test too early, or you took the test wrong. Pregnancy tests vary in their sensitivity (how soon they can detect the hormone hCG), and you may not have given your body enough time to produce enough hCG hormones that will show up on the test. Also, if you let a test sit for too long (after the instructions on the box tell you), the test is invalid. It is best to follow the instructions and wait until you have missed a period before taking the test. Most pregnancy tests come with two in a box, and it is a good idea to take both.

When is the earliest that I can take a home pregnancy test?

It is recommended that you wait until you have missed a period to take a home test. A missed period is often one of the first signs of pregnancy. If you cannot wait that long to find out and you know the day you may have conceived, then the earliest you can take a test would be 14 days from possible conception.

What if I take a couple of home pregnancy tests and get different answers?

If you have received different answers on multiple pregnancy tests, it is recommended that you get a blood test done to get an accurate answer.

Last Updated: 03/2011

Compiled using information from the following sources:

MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); [updated 2006 Feb 21]. Prenatal Testing; [updated 2006 Feb 20; reviewed 2005 Sept 13; cited 2006 Feb 22]. Available from: http://www.nlm.nih.gov/medlineplus/prenataltesting.html

U.S. Department of Health and Human Services, http://www.4woman.gov