Horizontal Line on Pregnancy Test Instead of Vertical: Why?

You’re pacing the room eagerly awaiting the result of your pregnancy test, only to finally look and see a confusing inconclusive result staring back at you. Talk about a cliffhanger.

A common issue with pregnancy test readings is a horizontal line appearing instead of the traditional vertical line – so what’s going on?

With a “plus sign” pregnancy test, a faint horizontal line crossed with a solid vertical indicates pregnancy. A colorless or faint horizontal line appearing when the test only uses vertical lines indicates that the test has expired or is defective.

A non-digital positive pregnancy test should typically show a plus sign or two bold vertical parallel lines, but with so many different types and brands of pregnancy tests on the market, a confusing result is bound to happen occasionally.

To make sense of it, let’s look at how and why this can happen and what to do next and explore other inconclusive results and what they mean.

Horizontal Line on Pregnancy Test Instead of Vertical

Seeing a horizontal line instead of a vertical one can be due to a defective or expired pregnancy test. It can also be a common issue with certain pregnancy test brands.

Let’s discuss how this can happen and what to do if you get this confusing result.

Faulty Test

Pregnancy tests contain antibodies that react to the hCG levels in your body (the hormone produced by your placenta during pregnancy), but as pregnancy tests near their expiration date, these antibodies slowly start to evaporate, leaving too few to detect hCG accurately.

In rare cases, the test may display a faint line running in a different direction than the one stated on the test. This is considered a faulty test, and you should take another test.

What the Manufacturers Have To Say

The issue of horizontal lines showing up instead of vertical lines seems to be a recurring issue with the pregnancy test brands Clearblue and Equate.

When questioned about the result of a faint horizontal line, Clearblue’s response was “It’s part of the internal structure of the test and is normal. As this is a ‘not pregnant’ result, retest in 3 days’ time if your period does not start.”

As for Equate’s Early Result Pregnancy Test, instructions state that the test stick should lie on a flat surface with the absorbent tip pointing to the left to avoid potentially viewing the test from the wrong perspective.

Equate states that: “for your result to be ‘Pregnant,’ the line in the round result window must run in the same direction (vertical) as the line in the oval control window and be of similar width.”

The only way in which a single horizontal line should appear in an Equate pregnancy test is if you are using the One Step test, which displays a single horizontal line in the round result window for a negative result.

What You Should You Do

Take another test in a few days. If you continue to see odd results and your period has not started, request a pregnancy test from your doctor.

You can also try a different test type, such as a digital pregnancy test that gives a “Yes/No” or “Pregnant/Not Pregnant” result for greater clarification.

TIP: Remember that your hCG concentrations are at their highest first thing in the morning, so try to always test using your first urine of the day to limit the likelihood of getting a false-negative result.

Horizontal Line on Plus Sign Pregnancy Test

In Plus Sign pregnancy tests with two windows (a result window and a control window), a single horizontal line in the result window acts as a negative or “minus” sign, indicating not pregnant. 

A vertical line accompanied by a horizontal line (however faint the line is) is typically an indication of a positive “plus” sign, indicating pregnancy.

Evaporation Line vs. Faulty Test

According to reproductive endocrinologist and Associate Professor of Obstetrics and Gynecology at the Yale School of Medicine Dr. Amanda Kallen, an evaporation line is:

“A slight streak that appears where the positive line on a test should be. These are colorless streaks, not faint lines and usually appear if a person has checked the result too late, taken the test incorrectly, or let the whole test get wet.”

A faulty test, meanwhile, occurs if the test has expired or become damaged in some way, leading to an invalid result with no lines appearing in either the test window or the control window (in the case of two-window pregnancy tests) or lines appearing where they should not.

White Indent Line on Pregnancy Test

“The white indent line is the space on a pregnancy test where the pink/blue dye would pool if you are in fact pregnant,” according to childbirth educator Lavanya Vasanthakumar.

“With some tests, you can see this when you aren’t really supposed to be able to see it. It usually means the test is negative or defective.”

Nevertheless, you should always keep testing to see if your result changes.

Some mothers on the What To Expect community forum discussed that, upon repeat testing, a white indent line later became faint pink and then became a clear bold positive line, so keep trying!

Dye Run Pregnancy Test

A dye run is when the pink or blue dye on a pregnancy test appears smudged or stained instead of displaying a clearly defined line.

Dye runs are very common on pregnancy test strips (as opposed to pregnancy test sticks where the test is held inside plastic).

Dye runs typically occur when the test result has been read too quickly, leaving inadequate time for the dye to settle, so it becomes oversaturated.

According to Medical News Today, “only urine that contains a sufficient level of hCG can cause the test’s dye to stain in a way that shows a positive result.”

For this reason, it’s best to retake the test according to the instructions and time frame to be sure it wasn’t a dud.

Flooded Pregnancy Test

Accidental urination on the pregnancy test window or urinating too long on the absorbent tip can result in the pregnancy test dye flooding the display windows with either all pink or all blue dye.

A working pregnancy test with a flooded window left to “clear” and settle for a few minutes should be able to reveal a solid line, either way, to indicate pregnant or not pregnant.

Pregnancy tests can also be “flooded” in the sense that it becomes overwhelmed with too much of the hCG hormone.

According to Forbes Health, this can happen when “elevated levels of the hormone overwhelm the test, causing it to produce a false negative. This tends to happen further along in pregnancy when levels of hCG increase.”

Related Questions:

Does an Indent Line Have Color?

Indent lines may appear grayish or white in certain lights and on certain types of pregnancy tests.

On a dip test, for example, a positive result should appear as two lines of the same color (usually red or blue), but if the second line appears faint, gray, or colorless, this indicates an indent and not a true positive result.

What Does a False Negative Pregnancy Test Look Like?

Using First Response as an example pregnancy test, a “Not Pregnant” result should display a single and solid vertical line of color.

A false negative test instead will show up as one very faint line or a line that isn’t clearly developed. False-negative results can be caused by faulty products or taking the test too soon.

Closing Thoughts

In summary, seeing a horizontal line instead of a vertical line on a traditional parallel line pregnancy test can point to a defective test, and we’d advise retaking the test in the next few days if you have yet to get your period.

In some cases, however, a faint horizontal line may point to a clear negative or positive result in the case of a “Plus” and “Minus” sign pregnancy test.

Always ensure you are taking the test correctly (i.e., not rushing to read the result, leaving it too long, or taking the test too early), and when in doubt, speak to your healthcare provider and request a test to know for certain.