Eager parents-to-be are not famous for their patience, especially when it comes to checking — and rechecking — whether or not their baby-making efforts have paid off. If you're among their ranks, chances are you've stockpiled home pregnancy tests and use them regularly. 

But though they're an affordable, easy-to-use and convenient way to find out if you're expecting, home pregnancy tests can be confusing, especially if you're very early in your pregnancy. Here's a guide to deciphering what those little lines or plus signs mean.

What does a faint line on a pregnancy test look like?

Depending on what kind of pregnancy test you use, you'll see a plus or minus sign or, more commonly, a line or two in the window that reveals the results. While the way the results are displayed varies between tests, they all detect the same hormone — human chorionic gonadotropin (hCG).  HCG is the hormone produced by cells that will become the placenta

Make sure you read the instructions on the pregnancy test packaging carefully so you know exactly what you should look for. A sensitive pregnancy test can detect hCG in your urine as soon as 8 to 9 days after ovulation, but most home pregnancy tests are not that sensitive. It's best to wait until the day of your missed period.

If you're pregnant but very early in your pregnancy, the line or double line on your pregnancy test will likely be barely visible, like a smudge of chalk. If you're farther along and the hormones are flowing, the line or lines will resemble marks drawn with a Sharpie.

If there's no line or positive result, it doesn't necessarily mean you're not pregnant (though that is a possibility). Instead, it could simply mean that there's not enough hCG yet for the test to detect. This is called a false negative result. The hCG level doubles approximately every 2 days — so the chance of a false negative occurring decreases the longer you wait to test.

What does a very faint line on a pregnancy test mean?

A very faint line on a pregnancy test usually means that implantation has occurred and you're in the early stages of pregnancy. But you'll want to test again a few days or weeks later to see if that line has become thicker and darker, meaning your pregnancy is progressing — and you can safely start getting excited!

It is possible to see a faint line on your pregnancy test and get your period a few weeks later, meaning that you're not actually pregnant, or were only briefly pregnant. This doesn't mean the test didn't work, but you might have experienced a very early and common pregnancy loss called a chemical pregnancy. It could also indicate other kinds of early pregnancy losses like an ectopic pregnancy.[1]

As upsetting as it can be, you probably never would have realized what had happened if that faint line hadn't clued you in, and the event will have no impact on your ability to get pregnant again.

If the results of your home pregnancy test are confusing or unclear, contact your OB/GYN to get a blood pregnancy test to confirm the pregnancy. This test measures the exact level of hCG in your blood and if there is any concern about the health of the pregnancy, the test can allow your doctor to trend the levels to ensure all is progressing well in the early stages.

What does a positive pregnancy test result look like?

A positive pregnancy test result will typically either show up as a plus sign, two double lines, or one line in a results circle or window, though there are other kinds of test results, including the digital ones that show the word "yes" or "pregnant" when they're positive.

Can a barely visible pregnancy test result be negative?

A barely visible pregnancy test result usually can't be negative — because it detected hCG — but it might indicate a false positive or an early pregnancy loss. However, false positive results that are not related to early pregnancy loss are incredibly rare.

Most home pregnancy tests claim to be up to 99 percent accurate — and when tested by lab technicians in ideal settings they probably are — but studies of home pregnancy tests used in the real world by women at home suggest they're slightly less reliable.[2]

Here are instances in which you might see a faint line on a pregnancy test but are not actually pregnant or have a nonviable pregnancy:

  • Menopause. If a woman in perimenopause or menopause misses her period and takes a pregnancy test, the results sometimes (but rarely) show up positive due to abnormally elevated levels of luteinizing hormone.
  • Fertility medications or other drugs. False positives can be caused by traces of fertility drugs or other medications containing hCG (though it's unlikely). If you received an hCG injection as part of fertility care, levels can remain elevated for at least seven days afterwards even if you're not pregnant. 
  • Early pregnancy loss. A false positive can also indicate a recent chemical pregnancy, ectopic pregnancy or another type of early pregnancy loss.
  • Illness. Very rarely, some cancers that interfere with hormonal production can result in a misleading pregnancy test.
  • Heterophilic antibodies. Women who work closely with animals, usually laboratory animals, can develop antibodies that bind erroneously to the test used for hCG detection.

Here's why you might be pregnant yet see a negative result on your pregnancy test:

  • It's too early. If it's very early in your pregnancy, concentrations of hCG may not have reached detectable levels yet. The best bet is to wait a week and test again.
  • You checked the results too soon. Of course you're impatient! But give the test the full time recommended on the package instructions to reveal results. You can use the timer on your watch or a kitchen timer to make sure you're waiting long enough.
  • Your urine is diluted. Good for you for staying hydrated. But if your urine is too diluted for the test to detect hCG, the results might be inaccurate. Taking the test first thing in the morning (when your urine is the most concentrated) is often recommended, but it's not necessary because modern-day pregnancy tests are super sensitive and can pick up even very low levels of hCG.[3]
  • The test is expired, or you made a mistake. If you didn't follow the instructions to the letter, or have a home pregnancy test that's expired, there's a chance that the results might be inaccurate.

If you get a faint positive pregnancy test, are you definitely pregnant?

If you get a faint positive pregnancy test, you are almost always pregnant, but it may be too early to celebrate. Home pregnancy tests differ in their ability to detect a pregnancy in women who have recently missed a period, either because of a chemical pregnancy or other reason.

If you have a negative test but think you might be pregnant, or vice versa, repeat the test one week after your missed period or talk to your practitioner. And remember, a blood pregnancy test from your OB/GYN is always more accurate.