When you’re trying to conceive (and certainly when you’re trying not to), the notion of being told you’re not pregnant when in fact you are can be utterly distressing. Can you get a false negative pregnancy test result? Yes, it’s possible. So how common are they, and what causes them?

The truth is, having that second red line show up when it’s not supposed to isn’t likely—but it can certainly happen under certain circumstances. Here, we’ve talked to experts to get their take on what can cause a false negative pregnancy test, as well as real women who’ve had to manage the very same conundrum. (Spoiler alert: Everything turned out just fine.)

In this article:
What can cause a false negative pregnancy test
How common are false negative pregnancy tests?
False negative pregnancy test stories

What Can Cause a False Negative Pregnancy Test?

A false negative pregnancy test isn’t exactly common, but it’s still more likely to happen than a false positive—an also-stressful scenario, except that the test says you’re pregnant when you’re not. In most (though not all) cases, a false negative occurs when you are pregnant, but the levels of pregnancy hormone in your body haven’t yet reached the test’s threshold of sensitivity. Here are a few reasons why this might happen:

You’re testing too early

An at-home pregnancy test works by checking your pee for hCG (human chorionic gonadotropin), a hormone your body produces when the fertilized egg attaches to the lining of your uterus, days after ovulation. For the most accurate results, it’s best to take the test a day or so after your missed period. If you take it earlier, the amount of hCG may be too scant for the test to pick up just yet, says Sean Esplin, MD, senior medical director for women’s health at Intermountain Healthcare in Utah. This can happen even if you’ve been diligently tracking your cycle. (After all, stress can delay ovulation, and if you’ve been trying to conceive in earnest, you know how stressful it can be!).

If your test registers a negative result but you suspect it’s wrong, simply retest in a few days. Fingers crossed, you should see at the very least a faint line on your pregnancy test, which likely confirms you’re pregnant (yippee!). If you continue to see a negative result but aren’t convinced, make an appointment with your ob-gyn. Your doctor can perform a blood-based pregnancy test, which, according to Esplin, are more accurate than at-home urine tests.

The test isn’t sensitive enough

Not all pregnancy tests are created equal. Some are designed to pick up the low levels of hCG that exist in the earliest stages of pregnancy, but others are not, explains Heather Lopez, MD, an ob-gyn with BJC Medical Group Women’s Health Care in St. Louis, Missouri. Some take less time to analyze your urine before producing an answer, and others require a longer wait time. What’s more, a pregnancy test isn’t very good at detecting hCG at all if it’s woefully past its expiration date.

So when you pick up a test at the store:

Check the expiration date. Make sure you’re using it well within that time frame.
Check the packaging. If you’re planning to test before a missed period, it should specifically say “early result” or “early detection.”
Check the instructions. If it says to wait two minutes for a result, set the stopwatch on your phone and wait for the full two minutes (and fight the urge to peek!)

Your urine isn’t concentrated enough

Experts advise taking a pregnancy test when you first pee in the morning—and for good reason. That’s because as you drink your morning coffee or tea, bottle of water, etc., you lower the concentration of hCG in your urine. And if your amount of hCG is low to begin with (because, say, it’s early in the pregnancy), you might end up with a false negative pregnancy test result. This can be avoided when you take your pregnancy test in the morning, Lopez says, before you’ve had anything to eat or drink yet.

You have a particular medical condition

Sometimes, a medical issue wreaks havoc on your body’s hCG levels, which can lead to a false negative pregnancy test. Consider, for instance, the very rare condition known as gestational trophoblastic disease, or GTD, which, according to Esplin, affects only about 1 in every 1,000 pregnancies. With GTD, tumors develop during the early stages of pregnancy, accompanied by sky-high levels of hCG, well above what you’d find in a normal pregnancy.

This then triggers what doctors call the “hook effect,” which is what happens when the urine sample contains too much of the substance that the specific pregnancy test is trying to detect, Lopez explains. “So instead of giving a positive result,” she says, “the test almost becomes overwhelmed by the excess amount of the substance it’s testing and gives a false negative.” But the hook effect is rare, she adds, and occurs less than 2 percent of the time.

More prevalent, but still uncommon, is a false negative pregnancy test brought on by an ectopic pregnancy, which occurs in only 1 in 40 to 1 in 100 pregnancies. In this condition, the fertilized egg implants outside the uterus, Esplin explains, and it’s usually diagnosed when patients visit the doctor because of abdominal pain and bleeding. In contrast to GTD, ectopic pregnancies have a slower, not higher, rate of rise in hCG. As a result, you might see a faint line on your pregnancy test, or none at all. An ectopic pregnancy is not viable and is in fact unsafe. If you’re feeling pain and bleeding, see your doctor right away.

How Common Are False Negative Pregnancy Tests?

From flushable strips to those that reveal how far along you are, pregnancy tests have grown a lot more sophisticated over the years. In fact, most at-home pregnancy tests are 99 percent accurate, Lopez says.

Subsequently, the likelihood of a false negative pregnancy test has gone way down. “In newer tests that are FDA approved, the risk of a false negative is very low,” Esplin says. Of course, accurate results don't just depend on the quality of the pregnancy tests, but how the tests are used and when. For this reason, it’s tough to zero in on exactly how common false negative pregnancy tests are.

Still, a 2019 Washington University study, shed a bit of light on the issue. The researchers evaluated 11 of the most-used hospital pregnancy tests and found that seven were somewhat susceptible to false negatives, two were highly susceptible and only two were not susceptible.

“The worst urine pregnancy test in this study gave false negative results in about 5 percent of urine samples,” notes Lopez (who wasn’t involved in the study). Your best bet is to choose an established brand of pregnancy test that tends to produce more reliable results, and retake the test a day or two later if the first reading is unclear.

False Negative Pregnancy Test Stories

It can feel isolating when you think you’ve experienced every early pregnancy symptom in the book, yet the test comes up negative. But you’re not alone. Many women have had to struggle with the doubt and confusion too. We asked three women to share their stories of false negative pregnancy tests—and what happened next.

“I experienced a false negative pregnancy test about 6 weeks into my pregnancy with the Sure-Aid One Step Pregnancy Test. I felt sad, but I had a gut feeling that I was pregnant and decided a couple of weeks later to go to a doctor, who would (luckily) inform us that we were pregnant.” -Sabrina B.

“I got a false negative pregnancy test with a Clearblue digital test. I took the test very early. We were trying to have a baby and I was incessantly tracking my cycle. I couldn’t wait to find out if I was pregnant, so I took the test three days before my missed period. It was negative, but when I took it the day before my missed period, it was positive!” -Marissa L.

“I went through IUI, and I was due for my blood tests 14 days after the injection to find out if I was pregnant or not. I took a home early pregnancy test the night before because I couldn't wait and I got a negative, so my expectations were very low for the blood tests the next day. Instead, it turned out I was pregnant, and I think it was just too early for the pregnancy test to detect the hormones the night before. I actually took another home early pregnancy test two days after; it was indeed positive!” -Monica G.

About the experts:

Sean Esplin, MD, is the senior medical director for women’s health at Intermountain Healthcare in Utah. He earned his medical degree from the University of Utah School of Medicine in 1993 and is double-board certified in obstetrics and gynecology as well as maternal fetal medicine.

Heather Lopez, MD, is an ob-gyn with BJC Medical Group Women’s Health Care in St. Louis, Missouri. She earned her medical degree from Florida State University College of Medicine in Tallahassee, Florida.

Please note: The Bump and the materials and information it contains are not intended to, and do not constitute, medical or other health advice or diagnosis and should not be used as such. You should always consult with a qualified physician or health professional about your specific circumstances.

Plus, more from The Bump:

When to Take a Pregnancy Test: The Best Timing for Accurate Results

Top 6 Home Pregnancy Tests to See If You're Expecting

15 Early Signs of Pregnancy