Horizontal Line on Pregnancy Test Instead of Vertical: Why?

A colorless or faint horizontal line appearing when the test only uses vertical lines indicates that the test has expired or is defective.

You should take another test.

This seems to be a common issue with Clearblue and Equate brand tests that use blue dye. Red or pink dye tests and digital tests are often seen as more reliable.

Special case note: If you are using Equate’s One Step Test, a horizontal line appearing in the first window indicates a negative result.

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

The Mayo Clinic advises:

“Always check the test’s expiration date. If it’s past that date, don’t use it. Read and follow the test directions carefully.”

Horizontal Line on Pregnancy Test Instead of Vertical

Seeing a horizontal line instead of a vertical one most likely indicates a defective or expired pregnancy test.

It can also be a common issue with certain pregnancy test brands.

I experienced this with my first pregnancy. The horizontal line was very faint, but it was definitely visible.

I tested again with a different brand the next day, and the results were positive!

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 (the hormone produced by your placenta during pregnancy) levels in your body.

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, Clearblues 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 Medical News Today, an evaporation line is:

“An evaporation line is a slight streak that appears where the positive line on a pregnancy test should be.

Evaporation lines are colorless streaks, not faint lines. They typically appear if a person waits for longer than the suggested time to read the test result.

An evaporation line can also appear if the test gets wet.”

A faulty test, meanwhile, occurs if the test has expired or become damaged in some way.

Age, damage, or a manufacturing defect can lead 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

“An ‘indent line’ (white line) is the space on the test where the dye would pool if you are in fact pregnant,” according to childbirth educator Lavanya Vasanthakumar.

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

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 take the test according to the instructions and time frame.

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.

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

According to Forbes Health:

“Elevated levels of the hormone can essentially overwhelm the test, causing it to produce a false negative. This is referred to as the ‘hook effect.’ The hook effect tends to happen further along in pregnancy, when levels of hCG increase.”

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).

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.