Home pregnancy tests are more common today than ever. Rather than having to go to your doctor or midwife for testing to determine whether or not you are pregnant, you will probably test within the comfort of your own home. It is very simple!

You do not need a prescription to purchase a pregnancy test. There are many different test kits available. You can purchase pregnancy tests at nearly any grocery or drugstore. It is important to understand how they work, however, before you purchase or use a kit.

How They Work

Human chorionic gonadotropin (hCG) is the pregnancy hormone that your body begins producing when pregnancy occurs. Pregnancy tests — whether blood or urine tests — detect the presence of hCG. The hormone hCG can be detected in your blood as early as eight to ten days after conception has occurred. It takes a few days longer for your body to begin excreting hCG in your urine.

Home pregnancy tests work by checking for the presence of hCG in your urine. You will place a few drops of urine into the test kit, or you urinate directly on the test stick. It will be filtered through special paper that has been treated with chemicals that can detect if there is any hCG present.

If hCG is present, the pregnancy test is said to be positive. Exactly how this will be indicated on your testing kit will be explained in the instructions. Some tests will show two lines, whereas other tests have a dark circle or a plus sign.

Consumers beware! Not all urine pregnancy tests are created equally. Different tests will measure different amounts of hCG, which is measured in mIU/mL (milli-international units per milliliter). There are tests that measure very small amounts of hCG — some as low as 20-25 mIU/mL — and other tests won't detect hCG until it reaches quantities that measure 250 mIU/mL. Remember the lower the number, the sooner you'll know.

Unfortunately, home pregnancy testing kits do not indicate on the box what amount of hCG it measures. To get this information, you must either call the nurses help line (offered by most makers of pregnancy test kits) or find the information online. A good source of information is the University of Kentucky School of Pharmacy.

While these tests can accurately indicate a pregnancy based on the presence of hCG, there are often false negatives because not everyone will have the same amounts of hCG in their urine that early. If you've taken a home pregnancy test and it was negative, do not assume you are not pregnant. Wait a few days and try again. It's quite likely that you simply tested too early.

Problem Pregnancy Tests?

Having problems with your pregnancy test? Maybe you just have a question about how to take it or what the results mean? Most tests offer a toll-free number you can call during normal business hours. These phone lines are staffed by registered nurses. This is a great source of help that is free and easy to access, so you should take advantage of it when you have questions.

One of the most common questions women have about a test is what effect common medications will have upon the test results. Generally most medications will not affect your test. This includes alcohol, acetaminophen, and birth control pills. The biggest exceptions are certain fertility medications that contain hCG. For this reason, some fertility patients are told by their doctors specifically not to take a pregnancy test — they may get a false positive. These patients will be monitored by the fertility specialists who are helping them through the process.

Likewise, you should be aware that if you took the pregnancy test and it was negative and you look at it later to reread it, it may show up as positive now. The test probably has limits on how long you can read the results, so be sure you read it within this time frame. You may get a false positive because the chemicals continue their reaction process, not because there is more hCG.