What Is a False Positive Pregnancy Test?

A false positive pregnancy test refers to a test result that shows a person is pregnant when in reality they're not. Pregnancy tests check the urine or blood for human chorionic gonadotropin (hCG), a hormone produced during pregnancy.

If hCG is detected, it typically means that the person is pregnant—but that's not always the case. Sometimes, a false positive result can happen due to a medical reason or the test not working correctly.

Although it's considered pretty rare, it is possible to get a positive reading on a pregnancy test when you're not pregnant. Over-the-counter (OTC) pregnancy tests are up to 99% accurate in detecting the presence of hCG when used correctly, but that doesn't mean they're completely foolproof.

In addition to errors with the test itself, there are also various medical explanations for having elevated hCG levels when you're not pregnant.

Test Inaccuracy and User Error

Pregnancy tests on the market are made to be as accurate as possible. The Food and Drug Administration (FDA) evaluates and monitors OTC pregnancy tests for reports on false positive test results or other issues. Still, there's a chance that the test could provide an inaccurate reading for several reasons.

Follow these expert-recommended tips to leave less room for error:

• Don't take the test too early during your cycle. Everyone's cycle is different, but most pregnancy tests are more accurate if taken a week after a missed period.
• Don't use the test when your urine is diluted from drinking water. Experts recommend testing when your urine is more concentrated to allow for hCG detection, which is usually first thing in the morning.
• Do check the test results during the recommended time frame. Checking the test too early or too late could make the results difficult to read accurately.
• Do check the test's expiration date before using it. Many test kits are good for one to two years, but check the label carefully to be sure.
• Do leave the stick in your urine for the recommended time period. Evaporation lines can get muddled if you leave the test in urine for too long or not long enough.

Biological and Medical Causes

A positive pregnancy test may be seen in several conditions in which hCG is present but there is no viable pregnancy.

Chemical Pregnancy

A chemical pregnancy, sometimes also referred to as a "biochemical pregnancy," is an early pregnancy loss that occurs just after an embryo implants in the uterus, usually at or before five weeks.

In these cases, an initial pregnancy test returns a positive result due to hCG remaining in the body, even though the chemical pregnancy doesn't progress to a clinical pregnancy.

Chemical pregnancies are thought to be quite common, making up 8% to 33% of all pregnancies, but many will go undetected unless a pregnancy test is taken.

Recent Miscarriage or Abortion

It’s possible to continue to test positive for pregnancy following pregnancy loss, either through miscarriage or abortion. This is because when a pregnancy ends, hCG levels remain in your system as they gradually decrease over a period of up to six weeks.

Pregnancy tests have the ability to detect even low levels of hCG, so using one in the days or weeks after a miscarriage can still prompt a positive test result.

It's possible to get a positive test reading after incomplete miscarriage, meaning that there may be tissue from the pregnancy remaining in the uterus that continues producing hCG. If this is the case, you'll want to seek medical attention right away.

Your healthcare provider may decide to monitor you in an outpatient setting or treat you with surgery or medication.

Medical Conditions

Though it's rarer, there are some medical conditions that can cause a false positive pregnancy test result. Typically, these are conditions that affect hormone levels and cause hCG to rise without a pregnancy.

While it definitely doesn't affect everyone, in some rare cases the following conditions can make a false positive result more likely:

• Pituitary gland disorders
• Certain cancers, such as ovarian cancer
• Kidney disease
• Urinary tract infections

Medications

Taking certain medications—particularly fertility medications—can result in a false positive pregnancy test reading. For example, hCG is likely to be detected if the test is taken shortly after using fertility drugs that contain hCG, such as Pregnyl or Profasi. With these medications, hCG can remain in your body for up to two weeks.

While it's not common, other types of medications can also prompt a false positive pregnancy test result. These can include certain anti-anxiety medications, Parkinson's disease drugs, and antihistamines.

Coping

Getting an ambiguous pregnancy test result can be emotionally draining, overwhelming, and frustrating. Know that you're not alone and that anything you're feeling is normal.

As immediate next steps, your healthcare provider or other healthcare professional will be able to perform a blood test to get a closer look at your hCG levels and clear up the pregnancy test results. From there, if treatment is needed, your healthcare provider will be able to walk you through the treatment and management options for your individual situation.

In situations of pregnancy loss, it's important to give yourself time to cope emotionally, as some people have an increased risk of developing clinical depression after this happens. In addition to leaning on friends and family as a support system, don't be afraid to seek help and ask your healthcare provider for counselor or support group recommendations.

A Word From Verywell

While they're typically accurate in many situations, sometimes pregnancy test results can be confusing. If you got one positive test result and another negative test result, it may be a good idea to wait a few days before taking the third test.

If you continue to get mixed results or suspect something more serious is happening, call your healthcare provider right away. They’ll be able to perform blood work to check your hCG levels and determine whether you’re pregnant or not.