Pregnancy Kits and Tests

If you suspect that you may be pregnant, you have several options to find out for sure. You can buy a home pregnancy test kit from a drugstore, discount store or the Internet, or you can see your health care provider, who can order a pregnancy test.

When you are pregnant, a hormone called human chorionic gonadotropin (hCG) is present in your blood and urine. When you are not pregnant, the level of hCG is so low that it's undetectable. In early pregnancy, the amount of this hormone increases rapidly, doubling every two to three days. Either a blood test or a urine test can confirm that you are pregnant by detecting this hormone. (After the first trimester, the amount of hCG gradually falls.)

A home pregnancy test kit, which tests your urine, can sense an hCG level of 25 to 50 milli-international units per millilter (mIU/mL). A blood test done by your provider is more sensitive and can detect hCG levels of 5 to 10 mIU/mL.

Home Tests

Home pregnancy tests cost less than $20, and some kits are multiple, allowing you to test your urine several times over a period of several days. The advantages of using a home pregnancy test are that the test is easy to use and that you can do the test in the privacy of your home. Make sure the test you buy has not passed its expiration date, because that can affect the test's accuracy. If used correctly, a home pregnancy test is 97 to 99 percent accurate.

Several types of home tests are available. With one type of test, you collect your urine in a container and then dip a special stick into the urine; or you collect your urine and then place it into a special container with an eyedropper. With the other type of home test, you hold a special stick in your urine stream. The stick or container, after a specified time, turns a particular color or shows a special symbol, indicating whether you are pregnant or not. Home tests come with instructions on how to use them, as well as toll-free numbers if you have questions about using them or about the results. To get an accurate result, it's important to follow the directions carefully.

If your home test is positive, meaning that you are pregnant, it's important to see your health care provider as soon as you can. Your provider will confirm that you are pregnant with a blood test and a pelvic exam. Good prenatal care is important for your health and for the health of your child. The earlier prenatal care begins, the better your chances for delivering a healthy baby.

Home pregnancy tests vary in how sensitive they are to the pregnancy hormone hCG. Some tests can detect lower levels of the hormone than other tests. And no home test can detect a pregnancy until the fertilized egg has become implanted in the uterus. In some cases, the egg doesn't become implanted until after the date when your next period should start. If you try the home test too early, you may get a negative result, even though you may be pregnant. Most of the kits tell you to do the test again in a week, regardless of the initial result. If you still think you are pregnant, but continue to get a negative result from a home test, see your health care provider.

A test that has passed it expiration date can produce an inaccurate result. Certain medications also can produce an inaccurate result. These include fertility medications, diuretics, some antihistamines, epilepsy drugs, medications for Parkinson's disease and tranquilizers. Most other medications, including birth control pills, do not affect the test results. Alcohol and illegal drugs don't affect the results, but if you are trying to become pregnant, you should avoid these substances.

Some of the common brands of home pregnancy tests with good sensitivity (15 to 25 mIU/mL) include Clearblue Easy, First Response Early Result and Answer Early Result. These brands are less sensitive (40 to 50 mIU/mL): e.p.t. and Fact Plus Select. Equate, another brand, can detect hCG levels only at 100 mIU/mL or greater.

Your Provider's Tests

Your health care provider can give you a more accurate pregnancy test, called a qualitative blood test or a beta hCG test. This measures the exact amount of hCG in your blood. This test can detect lower levels of hCG, so it can be performed earlier than a urine test. A blood test can tell if you are pregnant six to eight days after you ovulate.

If your provider uses a urine test instead of a blood test, the urine test available in a provider's office is much more sensitive than those sold as home tests. A provider's urine test may be able to detect the pregnancy hormone six days after you ovulate.

Diluted urine can affect the test results, causing a false negative (the results say you aren't pregnant even though you really are). If you are scheduled to take a urine test at your provider's office, don't drink a large amount of water before the urine collection.

As for the home test, certain medications can affect the results of a urine test done at your provider's office. These include fertility medications, diuretics, some antihistamines, epilepsy drugs, medications for Parkinson's disease and tranquilizers.