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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Does a faint line on a pregnancy test mean positive or negative? Find out for sure, plus learn how it differs from an evaporation line.
Maybe you’ve been TTC for a few months, and you’re anxious to see those two pink lines. Or maybe your period is a little late, and you’re wondering if a surprise baby is on the way. In either case, you’ll need a pregnancy test to give you some answers.
But what if you get a faint line?! What does that mean? You’ve got questions, and we’ve got answers. In this post, we’ll cover:
Here’s a video!
What Does a Faint Line on a Pregnancy Test Look Like?
A faint line looks different depending on which test you use. Most pregnancy tests use two parallel lines or a plus sign to indicate pregnancy.
- If you take a test with the plus sign, you’ll be looking for one dark vertical line (the control line) and one faint horizontal line crossing it.
- If you take a test with parallel lines, you’ll be looking for one darker line next to one faint line.
If you are testing early (before you’ve even missed your period), the faint line may be so faint it’s barely visible—almost like a tiny, tiny smudge. The further along you are, the darker the line usually becomes. You can see what this progression looks like in the image below:
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What Does a Faint Line Mean?
A true faint line—unlike an evaporation line—is usually a true positive.
A positive result (even a faint positive result) means that implantation likely occurred, and your body is beginning to produce HCG, a hormone that is vital for sustaining a pregnancy. This also means that you’re in the very early stages of pregnancy.
If you continue to test after you get a faint line, you should notice that the line grows darker as the days go on.
Can a Faint Line Be Negative?
Pregnancy tests have one goal: to detect hCG. When your test shows a faint line, it means that your body is detecting some hCG, which typically indicates pregnancy. Urine tests should display a positive test when 25 mIU/ml hCG is detected, according to a German study on pregnancy tests.
Unfortunately though, it is possible to see a faint line that goes away. It’s also possible to get your period shortly after seeing a faint line. This could point to a very early loss, like chemical pregnancy.
There are also some cases—beyond early pregnancy loss—that could cause a faint line to develop, even if you aren’t really pregnant. These situations include:
- Hormonal imbalances such as PCOS: Sometimes ovarian cysts may release hormones (including hCG) even if pregnancy isn’t achieved.
- Fertility medication: Some fertility medications may trigger positive results before you’re actually pregnant. If you’re currently going through fertility treatments, it’s a good idea to take a pregnancy test only when advised by your provider.
- Recent miscarriage: If your hCG levels have not returned to 0 mIU/ml hCG, it’s possible that a pregnancy test is still detecting residual hCG.
- Menopause: Early menopause can also trigger higher than normal hCG levels, which could lead to a false positive.
- Illnesses: Specifically, medications used for Parkinson’s disease and epilepsy can trigger a false positive.
- hCG diet: The hCG diet is a weight loss diet that incorporates this hormone into the treatment plan. Not surprisingly, if you’re on the hCG diet, you’ll likely get positive pregnancy results since the test is picking up those hormone levels.
The Difference Between a Faint Line and an Evaporation Line
Or, the faint line might not really be a faint line at all. It could be an evaporation line…
An evaporation line is the line that develops as urine evaporates off of the pregnancy test stick. Here’s how to spot the difference between a faint line and an evaporation line:
Thickness
An evaporation line tends to be skinnier than the control line; faint lines tend to be the same thickness as the control line.
Color of line
Most evaporation lines will be gray in color, not pink or blue like the control line. (Although, there have been reports that the blue lined pregnancy tests can show a light blue evaporation line. Ugh!)
Timing of the test
You should also consider the timing of the test. Evaporation lines appear as urine evaporates, which means it takes a several minutes for this to happen.
- If you take a test and immediately see a faint line, it’s likely a positive test albeit just faint.
- If you take the test and check back on the results after the allotted testing time frame, it’s probably an evaporation line.
Many mamas have taken tests, received a negative result, threw the test out, and then later noticed the line. This can cause some confusion, but generally those are late-appearing lines are evaporation lines. Always check your test within the specified time frame to help reduce the chance that you see an evaporation line.
What About Digital Pregnancy Tests?
Digital tests are much easier to read. Digital tests visibly display the words “Pregnant” or “Not Pregnant”—there are no lines to decode.
The downside? Digital tests can be very expensive, especially if you like to test before your missed period (and therefore might use more). Digital tests also need a higher concentration of hCG to yield a positive result, which could lead to a false negative if you test too early.
Think You’ve Got a Positive Pregnancy Test?
Congratulations! Check out this post to learn more about your positive pregnancy test.
Once you’ve received a positive test, it’s time to check in with your midwife or OBGYN. During your first appointment, your provider will take a blood test (which are more sensitive than the urine tests) to confirm your pregnancy, and from there, you can commence with your prenatal care.
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