(MayoClinic.com) Taking a home pregnancy test can be nerve-racking, especially if you're not sure whether you can trust the results. Know when and how to take a home pregnancy test — as well as some of the possible pitfalls of home testing.
Many home pregnancy tests claim to be accurate as early as the first day of a missed period — or even before. For the most reliable results, however, wait until one week after a missed period.
Shortly after a fertilized egg attaches to your uterine lining, the hormone human chorionic gonadotropin (HCG) begins production in the placenta and enters your bloodstream and urine. During early pregnancy, the HCG in your blood increases rapidly — often doubling every two to three days. Many home pregnancy tests can reliably detect this hormone in your urine one week after a missed period. Days earlier, however, some home pregnancy tests might not be as precise.
If it's important to confirm your pregnancy right away, ask your health care provider about a blood test to detect HCG. The blood test, which can be done in most health care providers' offices, is more sensitive than is the urine test.Are there different types of home pregnancy tests?
Various types of home pregnancy tests are available. With most tests, you place the end of a dipstick in your urine stream or immerse the dipstick in a container of collected urine for five to 10 seconds. A few minutes later, the dipstick reveals the test result — often as a plus or minus sign, a line or lines, a color change, or the words "pregnant" or "not pregnant" on a strip or screen.
Keep in mind that instructions might vary from kit to kit. Read the instructions carefully before you take the test. If you have questions about how to take the test or interpret the results, contact the manufacturer. Look for a toll-free number or the manufacturer's website in the package instructions.How accurate are home pregnancy tests?
Many home pregnancy tests claim to be 99 percent accurate on the day you miss your period. Although research suggests that some home pregnancy tests don't consistently spot pregnancy this early, home pregnancy tests are considered reliable when used according to package instructions one week after a missed period.Could medications interfere with test results?
Fertility drugs or other medications that contain HCG might interfere with home pregnancy test results. However, most medications, including antibiotics and birth control pills, don't affect the accuracy of home pregnancy tests.Could a positive result be wrong?
Although rare, it's possible to get a positive result from a home pregnancy test when you're not actually pregnant. This is known as a false-positive.
A false-positive might happen if you had a pregnancy loss soon after the fertilized egg attached to your uterine lining (biochemical pregnancy) or you take a pregnancy test too soon after taking a fertility drug that contains HCG. An ectopic pregnancy or menopause also might contribute to misleading test results.Could a negative result be wrong?
It's possible to get a negative result from a home pregnancy test when you're actually pregnant. This is known as a false-negative — and it's much more likely to occur than is a false-positive. You might get a false-negative if you:
Based on your test results, consider taking the following steps:
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