Home Pregnancy Tests

Taking a home pregnancy test can be an experience filled with concern and nervousness. We assembled the information below to help you deal with your concerns, find out how a home pregnancy test works, what can affect the results, and when to visit your health care provider.

The following information on home pregnancy tests has been adapted from the websites listed at the bottom of the page.

How do pregnancy tests work?

Pregnancy tests look for a special hormone in the urine or blood that is only there when a woman is pregnant. This hormone, human chorionic gonadotropin (hCG), can also be called the pregnancy hormone.

The pregnancy hormone, hCG, is made in your body when a fertilized egg implants in the uterus. This usually happens about 6 days after conception. But studies show that the embryo doesn't implant until later in some women. The amount of hCG increases drastically with each passing day you are pregnant.

Many home pregnancy tests claim they can tell if you're pregnant on the day you expect your period. But a recent study shows that most do not give accurate results this early in pregnancy. Waiting one week after a missed period will usually give a more accurate answer.

What's the difference between pregnancy tests that check urine and those that test blood? Which one is better?

There are two types of pregnancy tests. One tests the blood for the pregnancy hormone, hCG. The other checks the urine for this hormone. You can do a urine test at home with a home pregnancy test. You need to go to a clinic or see a doctor to have blood tests.

These days, most women first use home pregnancy tests (HPT) to find out if they are pregnant. HPTs are inexpensive, private, and easy to use. Urine tests will be able to tell if you are pregnant about 2 weeks after ovulation. Some more sensitive urine tests claim that they can tell if you are pregnant as early as one day after a missed period. 

If a HPT says you are pregnant, you should call your doctor or midwife right away. They can use a more sensitive test along with a pelvic exam to tell for sure if you are pregnant.

Blood tests can pick up hCG earlier in a pregnancy than urine tests can. Blood tests can tell if you are pregnant about 6 to 8 days after you ovulate (or release an egg from an ovary).

How do you do a home pregnancy test?

There are many different types of home pregnancy tests, or HPTs. Most drugstores sell HPTs over-the-counter. They cost between $8 and $20 depending on the brand and how many tests come in the box.

Most popular HPTs work in a similar way. The majority tell the user to hold a stick in the urine stream. Others involve collecting urine in a cup and then dipping the stick into it. At least one brand tells the woman to collect urine in a cup and then put a few drops into a special container with a dropper. Testing the urine first thing in the morning may help boost accuracy.

Then the woman needs to wait a few minutes. Different brands instruct the woman to wait different amounts of time. Once the time has passed, the user should inspect the "result window." Most brands tell users to repeat the test in a few days, no matter what the results.

How accurate are home pregnancy tests?

Home pregnancy tests (HPTs) can be quite accurate. But the accuracy depends on many things including the brand of test (some home pregnancy tests are more sensitive than others), when you use the test, how well you follow the instructions, and how well you interpret the results. If you mishandle or misunderstand the test kit, you may get poor results.

Most pregnancy tests have about the same ability to detect hCG, but their ability to show whether or not you are pregnant depends on how much hCG you are producing. If you test too early in your cycle or too close to the time you became pregnant, your placenta may not have had enough time to produce hCG. This would mean that you are pregnant but you got a negative test result.

Which brand of pregnancy test is the most accurate?

Some brands of tests can pick up lower levels of hCG than others. But limited research makes it impossible to say for sure which one is the best. Even so, 4woman.gov suggests that First Response, Early Result Pregnancy Test may be more sensitive than others.

Can I be pregnant and still get a negative result on a home pregnancy test?

Yes.  Every woman ovulates at different times in her menstrual cycle. Plus, embryos implant in the uterus at different times. So, the accuracy of HPT results varies from woman to woman. Other things can also affect the accuracy.  Accordingly, most HPTs suggest women take the test again in a few days or a week.

Sometimes women get false negative results (when the test says you are not pregnant and you are) when they test too early in the pregnancy. Other times, problems with the pregnancy can affect the amount of hCG in the urine.

If you have a negative result, it is always wise to consider this a tentative finding. Women should not use medications and should consider avoiding potentially harmful behaviors, such as smoking or drinking alcohol, until they have greater certainty that they are not pregnant.

Can anything interfere with home pregnancy test results?

Most medicines, over-the-counter and prescription, including birth control pills and antibiotics, should not affect the results of a home pregnancy test. Only medicines that have the pregnancy hormone hCG in them can give a false positive test result. A false positive is when a test says you are pregnant when you're not.

You should also talk to your health care provider if you miss your period for more than two months and you are not pregnant. Pregnancy is not the only possible cause of irregular menstruation. Women using birth control pills, for example, often miss periods and think, incorrectly, that their contraceptive method has failed them. If you get a negative result on an HPT after missing a period while you are on the pill, you should continue to take it as directed. Talk to your doctor before discontinuing the pill if you are repeatedly missing periods. Other things that can make you miss periods include:

For more information on pregnancy tests contact:

National Women's Health Information Center
Phone Number: 1-800-994-9662

Food and Drug Administration
Phone Number: (888) 463-6332

American College of Obstetricians and Gynecologists
Phone Number: (800) 762-2264 for publication requests only

Planned Parenthood Federation of America
Phone Number: (800) 230-7526

American College of Nurse-Midwives
Phone Number: (888) 643-9433

AACC Lab Tests Online: Pregnancy Tests