Home Pregnancy Tests
Compiled by Terri Isidro-Cloudas
If you suspect you're pregnant, chances are you're considering taking a home pregnancy test. And why not? They're readily available, easy to use, and can buy you peace of mind — not to mention quick results!
But before you head to the pharmacy to buy a home testing kit, learn the answers to some basic home pregnancy test questions from the National Women's Health Information Center.
How soon after conception is a pregnancy test effective?
Pregnancy tests, which are regulated by the Food and Drug Administration, have come a long way since the early to mid 1900s when toads, rats, and rabbits were actually used in testing. Today, over-the-counter home pregnancy kits provide privacy and fast results. They can detect pregnancy as soon as six days after conception or one day after a missed menstrual period. This is a major advantage in allowing women to seek the earliest prenatal care possible.
How do pregnancy tests work?
Pregnancy tests detect the presence of a hormone produced by pregnant women after conception, called human chorionic gonadotropin (hCG). In the 1970s, a method called ring or tube agglutination testing used a test tube containing prepackaged red blood cells to detect hCG in urine. If a ring showed at the bottom of the tube after addition of a urine sample, the test was positive. These tests are very sensitive to movement and human error so they're rarely used today.
The test kits you find in your drugstore today are much more sophisticated. Brands such as e.p.t. and First Response contain special antibodies that detect minute traces of hCG in urine. The antibodies are molecules coated with a substance that bonds to the pregnancy hormone if it's present. The tests are easy to use: A urine sample is combined with the antibodies in a special container and the test is timed. A color change indicates a positive or negative result.
Products such as Clearblue Easy use a testing method called "rapid assay delivery," which can give results in only three minutes and even inform the user if the test hasn't been done properly. This method combines a biochemical process with antibodies that detect hCG in a pen-shaped instrument.
How accurate are home pregnancy tests?
Although most manufacturers claim that home pregnancy tests are 99 percent accurate, inaccurate results may be more frequent due to improper usage, use of a product past its expiration date, exposure of the test to sunlight, and the presence of cancer in the user. It's very important to follow the package instructions exactly for results to be accurate. Regardless of the brand used or result obtained, most manufacturers recommend repeating the process a few days later to confirm results, because levels of hCG following conception are so low. The strength of each test varies, and the test may not pick up the amount of hCG hormone present the first time you test. You should definitely make an appointment to see your doctor as soon as you think you're pregnant. It's important to get prenatal care as early as possible, for your sake and for your baby's.
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