False Positive Pregnancy Test: Causes & Chances

If you are planning to start a family, experiencing morning sickness or nausea and missing your periods will make you happy, no doubt, but you need to be sure that you’re pregnant. You may consider a home pregnancy test, a convenient tool to find out if you are expecting. At-home pregnancy test kits are readily available over the counter and are easy to use. Most of these kits include sticks that are designed to detect the presence of the pregnancy hormone — hCG (human chorionic gonadotropin)- in the urine, a hormone that rises rapidly when an egg is fertilized (1). These home pregnancy tests claim to be foolproof, but in rare cases, the results could be off, i.e., the kit may give a false positive pregnancy test result. Yes, a pregnancy test can be false positive. Let’s scroll down to uncover more information about it.

What Is a False Positive Pregnancy Test?

When the pregnancy test indicates a positive result, but you are NOT pregnant, it is referred to as a false-positive pregnancy test (2).

Can You Get a False Positive Pregnancy Test?

Yes, it is possible to get a false and positive pregnancy test result from an at-home pregnancy test kit. It is important to notice that at-home pregnancy tests have about a 99% accuracy rate with claims like “highly sensitive” or “over 99&” on the package inserts of home pregnancy tests (3). The accuracy depends on how you use them and when you use them (4).

Other ways, including a blood test and an ultrasound, confirm the pregnancy with no chance of false positives.

How Common It Is?

Although rare, the chances of a false positive pregnancy test are less than 1 per cent of the time (5). This could lead to confusion and emotional distress.

Causes of False Positive Urine Pregnancy Test Results

Although the chances of a false-positive pregnancy test are rare, it may happen. Here are some common reasons why the pregnancy test may give you erroneous life-altering news.

1. You Had an Abortion/Delivery Recently

If you have delivered a baby recently or had an abortion or miscarriage in the past eight weeks, your hCG levels will still be there, diminishing slowly (6). If you take the pregnancy test during this time, it may show a false positive since the hCG levels in the body drop slowly and gradually after pregnancy ends.

2. You Had a Chemical Pregnancy

A chemical pregnancy is when a fertilized egg stops developing after implantation and never becomes an embryo. Technically, though, you might have been pregnant when you took the test, but this pregnancy ends in an early miscarriage. Around 10-20 per cent of pregnancies are estimated to end as undetected miscarriages. Chemical pregnancies end up really soon, and most women don’t even realise that they are pregnant. But they can cause the body to produce hCG, which could be picked up in a pregnancy test and thus show a false pregnancy test. A biochemical pregnancy may account for approximately 8-33% of all miscarriages, as per a 2017 study published in Obstetrics & Gynecology Science (7). 

3. You Have an Ectopic Pregnancy

As per Planned Parenthood, about 2% of pregnancies are ectopic (8). Ectopic pregnancies occur when a fertilized egg implants itself somewhere other than the uterus. The embryo cannot grow since there is no place for it to thrive outside of the uterus (9). An ectopic pregnancy is one of the reasons for a false-positive pregnancy test. But an ectopic is a medical emergency. If you suspect an ectopic pregnancy, you must seek medical help.

4. You Have Some Medical Problem

Certain medical conditions such as cancers of the ovary, bladder, kidney, lung, breast and stomach, gestational trophoblastic diseases, ovarian cysts, kidney disease, urinary tract infections, adenomyosis, and more can cause a woman’s hCG to rise and lead to a false-positive test result (10) (11).

5. You Are Nearing Menopause

Women who transition to menopause often have high levels of hCG. This can cause a false-positive test result in some older women. If you’re nearing menopause and take a pregnancy test, chances are that it will show a false-positive test.

6. Your Test Showed an Evaporation Lines

If you don’t follow the manufacturer’s instructions properly, you might possibly get a false-positive. You’ll have to make sure you check the results within the instructed time frame. Letting the test sit longer than the specified time period can cause you to confuse the urine evaporation lines for a positive test line.

7. You Have a Defective Pregnancy Test

An expired or defective pregnancy test can yield false results. So you must check for a valid test before use.

8. You Took the Test Too Early

Some highly sensitive tests can detect a positive just days after ovulation. Hence, it is recommended that you wait at least a week after a missed period. Testing too early is one of the common reasons for a false-positive pregnancy test.

9. The Urine Sample is Contaminated

If the urine sample contains any impurities like soap or blood, you might read an inaccurate result.

Medication That Can Cause a Pregnancy Test to Be False Positive

If you are receiving fertility treatment in the form of shots of hCG or gonadotropins for ovulation, you may get a false-positive test result.

Apart from that, medication like antipsychotics, antihistamines, anti-anxiety medications, diuretics,  medicines for Parkinson’s disease and drugs like methadone, chlordiazepoxide or promethazine can cause false-positive pregnancy tests.

What Is Phantom hCG Test and How Is it Related to False Positive Pregnancy Test?

A phantom hCG is a positive blood pregnancy test with a woman who is not pregnant. Certain chemicals in an individual’s body interfere with the testing kit, causing it to show a false positive.

You may have a reason to check whether you’re getting a Phantom pregnancy positive test if your urine test is negative.

What Is the Reason for False Positive Blood Pregnancy Test Results?

If you’ve realized that you have got your U-check pregnancy test false positive, it is advised to have a healthcare professional confirm with a blood pregnancy test. Blood tests can detect hCG at lower levels than urine tests and, therefore, are more reliable as they can detect a pregnancy earlier.

However, a qualitative hCG blood test can also be false positive or negative for some reason. Some of the reasons of how can you get a false positive pregnancy test are common for urine or blood tests.

Specifically, certain medications (as mentioned above), tumours, ovarian cancer, blood or protein in the urine and multiple pregnancies cause the presence of high hCG levels in a woman. Besides, chemical pregnancy, menopause and fertility treatment are also some of the causes that can increase the chances of getting a false positive pregnancy test.

Ways to Avoid False Positive Pregnancy Tests

Accurate results from a pregnancy test can be achieved by being attention to detail and optimising the test with a proper technique. Follow these steps for accurate testing.

• Check the expiry of the home pregnancy test kit before using it.
• Keep your test kit in a cool and dry place away from direct sunlight.
• Read the instructions carefully before using the test.
• Take the test first thing on the morning with first-morning urine to get accurate results.
• Refrain from drinking excessive water or fluids before taking the test.
• Use a clean and dry cup for collecting urine.
• Use a timer to check for results accurately.

What Should You Do After Getting a False Positive Pregnancy Test?

A false positive pregnancy test result can cause emotional distress and confusion, but there are some things you must remember to do after getting it. First of all, schedule an appointment with a doctor for a confirmation on your pregnancy status. Make sure to:

• Schedule your blood test to get an confirmation of exact levels of hCG levels.
• Schedule an ultrasound after consulting a doctor, if necessary.
• Discuss all your doubts related to pregnancy, false positive, any medication you are on, or having any health condition.
• Complete all your tests and document you medical history to ensure a proper dignosis.
• Wait 48-72 hours beforehand if you wish to retest.

FAQs

1. Can stress cause false pregnancy test results?

No, there is evidence to show that stress can directly lead to a false pregnancy test result.

2. Can I be five weeks pregnant after getting a negative test result?

Yes, it is possible to be five weeks pregnant with a negative test result, especially if the test was expired, taken a little too early, or incorrectly. It is best to consult a doctor for a confirmed result.

3. What’s the best time to take a pregnancy test?

The optimal time to take a pregnancy test includes the first day of your missed period, One week after the missed period, Early morning, 14 days after conception, and 21 days after unprotected intercourse.

If your at-home pregnancy test has read a positive result, it is recommended that you consult a doctor to confirm the result with a blood test. If you find out for sure that you are pregnant, you must see your doctor regularly. It is important to take care of your health and undertake early prenatal care under their supervision to maintain a healthy pregnancy.

References/Resources:

1. Pregnancy; FDA; https://www.fda.gov/medical-devices/home-use-tests/pregnancy

2. How early can home pregnancy tests show positive results?; UT Southwestern Medical Center; https://utswmed.org/medblog/home-pregnancy-tests/

3. Gnoth. C, Johnson. S; Strips of Hope: Accuracy of Home Pregnancy Tests and New Developments; Geburtshilfe Frauenheilkd.; PubMed Central; https://pmc.ncbi.nlm.nih.gov/articles/PMC4119102/; July 2014

4. Pregnancy tests; OASH; https://womenshealth.gov/a-z-topics/pregnancy-tests

5. 7 Reasons Your Pregnancy Test Gave A False-Positive; The Source; https://www.thesource.org/post/reasons-your-pregnancy-test-gave-a-false-positive

6. Butts. S. F, et al.; Predicting the decline in human chorionic gonadotropin in a resolving pregnancy of unknown location; Obstet Gynecol.; PubMed Central; https://pmc.ncbi.nlm.nih.gov/articles/PMC3752097/; August 2013

7. Lee. H. M, et al.; Etiological evaluation of repeated biochemical pregnancy in infertile couples who have undergone in vitro fertilization; Obstet Gynecol Sci.; PubMed Central; https://pmc.ncbi.nlm.nih.gov/articles/PMC5694731/; November 2017

8. Ectopic Pregnancy; Planned Parenthood; https://www.plannedparenthood.org/learn/pregnancy/ectopic-pregnancy

9. Ectopic Pregnancy; ACOG; https://www.acog.org/womens-health/faqs/ectopic-pregnancy

10. Betz. D, Fane. K; Human Chorionic Gonadotropin; StatPearls Publishing; https://www.ncbi.nlm.nih.gov/books/NBK532950/

11. McCash. S. I, et al.; Reducing False-Positive Pregnancy Test Results in Patients With Cancer. Obstet Gynecol.; PubMed Central; https://pmc.ncbi.nlm.nih.gov/articles/PMC5724973/; October 2017

Also Read:

Simple (DIY) Pregnancy Tests
Positive Pregnancy Test
Negative Pregnancy Test But No Period
Taking a Pregnancy Test at Night – How Accurate Is It?

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