A falsely positive pregnancy test can be devastating – especially for women who have difficulty getting pregnant or who are actively trying to get pregnant . The last thing you want to do is jump for joy – only to find out later that you are not actually pregnant. On the other hand, if you actively try to become pregnant it may be just as terrible to get a positive pregnancy test . Keyword: Panic visit to your gynecologist, only to find that you are actually not pregnant and have nothing to fear.
Fortunately, false-positive pregnancy tests are rare, but they can occur . Here are some of the common causes of a false-positive pregnancy test.
To understand how a false-positive pregnancy test can work, it is important to first know how a pregnancy test works.
At home pregnancy tests check for the hormone hCG. HCG is the abbreviation for human chorionic gonadotropin that the body produces during pregnancy. Immediately after a fertilized egg adheres to the lining of the uterus, the placenta forms and hCG is produced, according to the Mayo Clinic . A blood test can detect hCG about 11 days after conception, and a urine test can detect it 12 to 14 days after conception, according to the American Pregnancy Association . The hCG level of a woman usually doubles every 72 hours in the 8th to 11th week of pregnancy. Then it stays constant and decreases after delivery.
A pregnancy test at home is said to detect hCG in urine . When the hormone is present, it triggers a chemical reaction and the test signals that you are pregnant. If hCG is not present, the test says that you are not pregnant. In many tests, two lines mean that you are pregnant and one line that you are not pregnant. However, this depends on the test brand. Some tests use plus and minus signs. Some digital pregnancy tests have a screen that clearly states "pregnant" or "not pregnant."
Seems easy, right? As Ina Garden would say, "how easy is that?" Usually pretty simple. Most home pregnancy tests indicate an accuracy of 99 percent, as the Mayo Clinic states. Ultrasound examinations can usually detect pregnancy only in the fifth or sixth week after the first occurrence of a pregnancy sack . That's why testing at home is so useful. But sometimes other factors can falsify the results of a pregnancy test and tell you that you are pregnant when you really are not.
The most likely reasons for a false positive pregnancy test are:
1. You let the test sit too long before you look.
If you are performing a standard pregnancy test with line indicators, it is important to review the results in the specified timeframe. If you wait too long before reading the results, the test urine can evaporate, making it look like you have two lines instead of just one. "Often, people will see lines of evaporation when the urine evaporates from the test," says Jamil Abdur-Rahman (19459034), a doctor admitted by the Women's Health Authority, to SELF. This could make the test look like a weak second line – which makes it positive – but actually only one.
The best way to avoid this: Read the pregnancy test instructions and follow them carefully. For example, the popular pregnancy test stamp First Response instructs users to wait three minutes after the test is performed and then read it as soon as possible.
. 2 The pregnancy test has expired.
The second most common reason why his patients achieve false positive results is, according to Drs. Abdur-Rahman that the test has expired. If a test expires after the expiration date, the chemical that detects hCG will not always function properly and you are more likely to be misread. "The test can expire and the probability of a false positive result increases," says Dr. Abdur-Rahman.
. 3 They take fertility drugs that increase hCG levels.
If you perform a pregnancy test too soon after taking a fertility drug that contains hCG – as some injections that are often part of in vitro fertilization (19459004) could be false-positive.
"[This happens to] Women who are very motivated and try to understand, and they will often perform the pregnancy test early and see a positive outcome, which is obviously very exciting for them at first", Zev Williams MD, gynecologist and assistant professor in the Department of Obstetrics and Gynecology and Women's Health at the Albert Einstein College of Medicine, reports SELF. "But it could also be the result of the fertility medication they have taken in. We caution patients that they have false hopes when they find that the test is positive."
. 4 They had an extremely early miscarriage.
You could get your period a few days after a positive pregnancy test and assume that you had a false positive result. However, it may be that you were pregnant but had a miscarriage very early. "It's not that the test is wrong – he was completely accurate in taking the hormone [hCG]," Dr. Williams. "Unfortunately, this was not a healthy pregnancy." Doctors refer to this early pregnancy loss as Chemical Pregnancy .
Most miscarriages occur in the first 13 weeks of pregnancy, and although there are no real statistics, it is estimated that many miscarriages occur before a woman even knows she is pregnant A pregnancy is lost according to the American Pregnancy Association shortly after implantation. This is usually due to chromosomal abnormalities in the fertilized egg. Chemical pregnancies make up 50 to 75 percent of all pregnancies from miscarriages.
Persons with a chemical pregnancy often experience bleeding (if they have a miscarriage) at exactly the time they were expected to. Therefore, it is easy to assume that you just had a false positive test ult.
5. You have a residual hCG in your system after delivery or miscarriage.
After giving birth or a miscarriage, the hCG can remain in your body for months, says dr. Williams. The American Pregnancy Association estimates that it takes four to six weeks for hCG levels to return to normal after miscarriage . This is because part of the placenta remains in the body and can continue to produce hCG for a short time. "As long as there are viable, growing placental cells in the woman, these tests can be positive," Dr. Williams.
. 6 They had an ectopic pregnancy.
A ectopic pregnancy occurs when a fertilized egg grows outside of the uterus – usually in an oviduct – instead of within  the uterus, after Mayo Clinic . However, ectopic pregnancy can also occur in other reproductive areas such as the ovary or cervix. An ectopic pregnancy is not viable because the embryo is not in the uterus where it can grow and thrive. The embryo will still produce hCG, which can lead to a false positive pregnancy test.
According to the Mayo Clinic, an ectopic pregnancy can be life-threatening. Call your doctor right away if you experience any of the following symptoms:
- Severe pain in your abdomen or pelvis during pregnancy
- vaginal bleeding (this is unusual)
- Severe dizziness or drowsiness
- Other symptoms, you worry
If you get a positive pregnancy test, it is best to consult your doctor.
Your gynecologist can do a blood test to further examine the hCG level and resolve any issues Pregnancy test error. Dr. Abdur-Rahman says he views pregnancy testing at home rather as "screening tests" – a blood test is a diagnostic test that can actually confirm that you are pregnant. If a blood test confirms that you are pregnant, your gynecologist can continue to monitor the level of hCG in your blood to make sure your pregnancy is developing properly before an ultrasound will reveal more details.
And if you get a negative pregnancy test, you know that the wrong negative is possible. If you perform a pregnancy test at home too early, the hCG hormone may not be absorbed. But, as we explained above, these hormones should double every 72 hours in a healthy pregnancy. "The longer you wait, the more likely you are to get pregnant," Dr. Williams. He recommends running another pregnancy test two days later to check the results.