What does a faint negative pregnancy test mean

After getting a negative result on a home pregnancy test, it's fair to conclude that you're not pregnant. However, if you happen to glance back at the test later in the day, you may be surprised to see that a positive line has magically appeared. There are a few reasons why this can happen. However, in most cases, the originally reading of the test, "not pregnant," is typically the correct one.

What Are Evaporation Lines on a Pregnancy Test?

The instructions on most pregnancy tests will advise you to read the results within a certain window of time. This usually ranges between a couple of minutes up until 10 minutes later. If you see a positive result beyond this time frame, you may be left second-guessing the results.

However, the false-positive reading, in this case, is due to something called an evaporation line. Evaporation lines are not indicative of a true positive result.

Evaporation lines happen when the urine that was on the test area starts to dry. The chemical composition of the urine sample changes due to evaporation. As a result, the test may start to display a positive line. After the allotted time has passed, you should discard the pregnancy test to avoid confusion.

If you follow all of the instructions correctly, you may notice a thin, faint test line that appears within a few minutes. It can seem at first that the line is too faint to count, but after 10 minutes, it darkens. There are several possible explanations for this line:

• Chemical pregnancy: When implantation of a fertilized egg happens, hCG is produced, even though that egg may not be viable. Chemical pregnancies are the most common cause of early miscarriage. Without taking a pregnancy test, the miscarriage may easily be mistaken for a regular period.
• Lower sensitivity test:You might need a test with higher sensitivity levels so that you can get accurate results earlier in the pregnancy. Look for "early results" indicated on the test label.
• Too early in your cycle: If you test earlier than 10 to 12 days past ovulation, the hCG hormone may not be high enough to produce more than a very faint line. The best time to test is after your period is late, or 2 weeks after you ovulated.
• Too much fluid: You can dilute your urine sample if you are urinating too frequently or drinking too many liquids—this is why first-morning urine samples are recommended for pregnancy testing.

False Negative Results

While true false negative results are rare, there are multiple reasons why you could get a negative or faint result even if you are actually pregnant, such as not waiting long enough into your cycle to test or testing with diluted urine. Always use a sample from your first-morning urine (which is more likely to have higher concentrations of the pregnancy hormone, hCG).

If you are still unsure about pregnancy test results, wait a few days and test again. If you have any questions or concerns about whether or not you could be pregnant, consult with an OB/GYN.

A Word From Verywell

It can very stressful to see conflicting results on a pregnancy test, such as faint lines or evaporation lines. If you're unsure about your results, retest in a couple of days or talk to your doctor about a follow-up blood test for confirmation. Following the directions on your pregnancy test helps avoid the confusion or disappointment of a false positive.

Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

By Robin Elise Weiss, PhD, MPH
Robin Elise Weiss, PhD, MPH is a professor, author, childbirth and postpartum educator, certified doula, and lactation counselor.

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Many people repeat home pregnancy tests, and then grow concerned if the result changes from positive to weakly positive. Is it a miscarriage, an error, or something else?

If you had a dark line before and now you have a faint line, there could be several explanations for this, other than miscarriage. You may have consumed too much water prior to the test, or not enough. You may have accidentally used the test incorrectly, or something else in your urine may have interfered with the test.

How a Pregnancy Test Works

Home pregnancy tests are based on the detection of the pregnancy hormone human chorionic gonadotrophin (hCG) in your urine. When hCG is detected, the test will return a positive result. When hCG is not detected, the test comes back negative. A positive result is usually indicated by two lines, either side-by-side or in a plus sign.

Depending on whether you take the test as instructed, the results may sometimes be uncertain or incorrect. A review study found that in 1982, pregnancy tests had a nearly 25% rate of false negatives, and only one-third of users reported reading test instructions. In the early 1990s, technology increased testing reliability to 99% sensitivity, with 76% of users reporting that they read test instructions.

User Error

While today's tests are more foolproof, user mistakes can still occur during urine collection for the test, as well as when interpreting results. Some tests are performed by:

• Placing a test stick into the urine mid-stream while urinating
• Urinating into a cup and dipping a test strip into the urine
• Urinating into a cup and using an eyedropper to place a small amount of urine onto a testing device

In one study, a hundred women were asked to test all three methods. The third test, using the eyedropper, failed to provide a result 24% of the time. And more than 30% interpreted the eyedropper and strip tests differently than trained study coordinators.

While the stick test only failed to provide a result 5% of the time, and the women and researchers agreed with results 99% of the time, user error is still possible if a user does not fully saturate the strip on the stick. It is generally designed to collect urine under a stream for 7 to 10 seconds. Small variations can make a difference as to whether a test is accurate or inaccurate.

What a Faint Line Means

Although hCG levels increase exponentially during early pregnancy, that doesn't mean that the pregnancy test line will necessarily get darker as each day passes. Things are not always that simple.

Although the line should be darker in relation to higher concentrations of hCG, the actual amount of hCG in a sample of urine can vary. This is due in large part to the concentration of your urine at any given time. This can fluctuate dramatically throughout the day depending on how much fluid you drink and how frequently you urinate, among other things.

The more you drink, the more diluted the hCG in your urine will become. The same can occur if you urinate frequently and constantly excrete hCG from your body.

As a general rule, if your urine is light or clear, it is less concentrated and may not produce a distinctive result on a home pregnancy test. In theory, if you have darker urine, you may get a more distinguishable line than if you test with lighter urine a day or two later.

Because of this, taking multiple tests to check the color of the line is not a reliable means of monitoring the development of early pregnancy. Even though you will likely pass more hCG in your urine as the pregnancy progresses, a home test will not necessarily reveal a darker line hour-by-hour or day-by-day.

Urine Tests vs. Blood Tests

Blood is far more reliable for monitoring hCG levels. That's because blood maintains a fairly steady composition at all times, thus making it easier to monitor changes in chemicals such as hCG. That's why quantitative hCG blood tests over a period of days are far more reliable that urine tests for monitoring hCG levels.

Blood tests can detect pregnancy nine to 10 days after ovulation. However, your doctor won't suggest a blood test until after your period is due and only if there is a medical need.

If you have had pregnancy complication in the past or are worried about miscarriage, don't waste money buying multiple home pregnancy tests. Instead, speak to your doctor about a blood test to confirm the pregnancy and ensure that it is progressing as it should.

Changes in Test Results

If you get a negative result on a home pregnancy test after having gotten a positive result, this could be an understandable cause for concern and confusion. While it may simply be a false negative (usually as a result of a user error), it could also be the result of a very early miscarriage, known as a chemical pregnancy.

A chemical pregnancy is one that occurs before the fifth week of gestation and well before the fetus can be visibly detected on an ultrasound. It is believed to affect as many as 25% of pregnancies that end in miscarriage.

If a chemical pregnancy is suspected, your doctor may test the hCG levels in your blood several times. Decreasing levels may provide evidence that a chemical pregnancy has, in fact, taken place.

Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

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3. Gnoth C, Johnson S. Strips of hope: Accuracy of home pregnancy tests and new developments. Geburtshilfe Frauenheilkd. 2014;74(7):661-669. doi:10.1055/s-0034-1368589

4. UNC School of Medicine. Time to conceive: Pregnancy test instructions.

5. Montagnana M, Trenti T, Aloe R, Cervellin G, Lippi G. Human chorionic gonadotropin in pregnancy diagnostics. Clinica Chimica Acta. 2011;412(17-18):1515-1520. doi:10.1016/j.cca.2011.05.025

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By Krissi Danielsson
Krissi Danielsson, MD is a doctor of family medicine and an advocate for those who have experienced miscarriage. 

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