It's a uniquely devastating emotion. Yup, you could probably do without the panicked verification trip to the ob-gyn, just to learn there was nothing to stress over. Thankfully, experts note that false positive pregnancy tests are rare. Unfortunately, though, they can happen. Here are some of the most common causes of a false positive pregnancy test, along with some additional information that can help you put it all into context.
Let's start with the absolute basics just to make sure we're all on the same page. That's simple enough to understand. But it's understandable if you're a little fuzzy on the details of what these devices actually look for to identify a pregnancy.
At-home pregnancy tests check for the hormone hCG. HCG is short for human chorionic gonadotropin, which the body creates during pregnancy. Right after a fertilized egg attaches to the uterine lining, the placenta then forms and starts producing hCG 1. A blood test can detect hCG about nine days after conception, and a urine test can detect it 12 to 14 days after conception, according to the Cleveland Clinic , although it varies—some especially sensitive urine tests can detect a pregnancy even earlier.
Then it remains consistent and starts to go down after delivery. Back to top. An at-home pregnancy test is designed to find hCG in pee 2. If the hormone is present, it triggers a chemical reaction and the test signals that you're pregnant. If hCG is not present, the test will say you aren't pregnant. Some tests use plus and minus signs. Some digital pregnancy tests have a screen that plainly reads "pregnant" or "not pregnant.
Seems simple, right? As Ina Garten would say, "How easy is that? Ultrasounds typically can't detect a pregnancy until a little later in your pregnancy and that's why at-home tests are so useful. If you take a standard pregnancy test with line indicators, it's important to check the results according to the specific instruction of the test. If you let it sit too long before reading the results, urine on the test can evaporate and make it look like you have two lines instead of just one.
That might cause the test to look like it has a faint second line—making it positive—but it really only has one. The best way to avoid this: Read the pregnancy test's directions and follow them exactly. With most tests, you place the end of a dipstick in your urine stream or dip the dipstick in a container of collected urine.
A few minutes later, the dipstick reveals the test result — often as a plus or a minus sign, one line or two lines, or the words "pregnant" or "not pregnant" on a strip or screen. Follow the test instructions for how long to wait before checking results — usually two or more minutes. Most tests also have a control indicator — a line or symbol that appears in the result window.
If the line or symbol doesn't appear, then the test isn't working properly. Try again with another test. Some home pregnancy tests are more sensitive than others. In other words, the amount of HCG needed to be detected in the urine to produce a positive test result is lower in some tests. Always check the test's expiration date and read the instructions carefully before you take the test. Many home pregnancy tests claim to be 99 percent accurate.
However, home pregnancy tests differ in the ability to diagnose pregnancy in women who have recently missed a period. If you have a negative test but think you might be pregnant, repeat the test one week after your missed period or talk to your health care provider.
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.
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, menopause or problems with your ovaries also might contribute to misleading test results.
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. You might get a false-negative if you:. There is a problem with information submitted for this request.
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Error Include a valid email address. This may represent an early pregnancy or may simply be an evaporation line. If you read the test after the recommended time in the instructions, the results might be a false-positive since the evaporation line may show up more clearly. Each test brand has specific instructions, so follow them closely. Like most consumer goods, pregnancy tests expire and are sometimes used wrong. Using a test incorrectly or using an old one can lead to a false-positive result.
Here are a few tips to avoid user error:. Diluted urine from excessive water-drinking can affect the accuracy of the test.
Set a timer to keep track. The next two points are unique in that they indicate the presence of BhCG in the body so they are technically accurate in giving a positive result. However, an ectopic or chemical pregnancy sadly is not viable. As the pregnancy grows, it can cause the tube to burst rupture. A rupture can cause major internal bleeding. This can be a life-threatening emergency that needs surgery.
If you think you have an ectopic pregnancy, or have a positive pregnancy test paired with severe pain on one side of the lower abdomen and spotting, seek immediate medical help as soon as possible. A chemical pregnancy is a miscarriage that happens before week five of the pregnancy when an embryo implants in your uterus but it never takes hold.
The loss happens so early that you may not even know you're pregnant. However, the embryo produces hCG and can cause a false-positive on a pregnancy test. This situation is known as a chemical pregnancy. The emotional strain from false-positive results can be severe and mentally taxing for you and your family.
We recommend waiting to use at-home pregnancy tests until one week after the expected start of your period.
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