A faint line on a pregnancy test can mean pregnancy or inaccurate results - here's how to get correct results

• A faint line on an at-home pregnancy test can mean you're in the earlier stages of pregnancy.
• But, it can also mean the test wasn't taken properly, so its important to follow instructions.
• If you get a faint line, start taking a prenatal vitamin and schedule a doctor's appointment.

Understanding the results of an at-home pregnancy can feel surprisingly complicated at times. A pregnancy test measures the presence of the hormone human chorionic gonadotropin, or hCG, which is produced by an embryo. Though not as accurate as a pregnancy test at the doctors, an at-home pregnancy test can measure hCG levels with 97 to 99 percent accuracy.

Pregnancy tests with blue or pink dye typically show one line if the result is negative and two if hCG is detected, meaning the result is positive. If you get any type of second line, even a faint one, you are pregnant, says Jennifer Lincoln, MD, an obstetrician in Oregon. "A line is a line, whether faint or dark. Any line means pregnant," she says.

Here is what to do if you get a faint line on your pregnancy test at home according to an expert.

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

If you take a pregnancy test and a faintly colored second line appears, it usually means you are pregnant. Here's why you could be getting a faint line:

It's early in your pregnancy. If you take a pregnancy test in the days immediately before or after a missed period, the test will only detect small amounts of hCG, which can show up as a faint line. Most pregnancy tests on the market only work properly if you take them a week or more after missing your period, says Cara Delaney, MD, a gynecologist and instructor at the Boston University School of Medicine.

You have a chemical pregnancy. A chemical pregnancy is a type of miscarriage that happens very early on in pregnancy. It can cause a false positive result or a faint line on a pregnancy test because the brief pregnancy produces a small amount of hCG in your body.

You made a mistake in taking the test. "If you wait too long to read the test it can dry and leave a line that can be misinterpreted as a positive test," says Lincoln. Most pregnancy tests include instructions to read the results around three to five minutes after testing.

Important: If a test gets wet or is left out too long, an evaporation line, which is a faint streak may appear on a pregnancy test. This does not mean you're pregnant. This line should be colorless, which is how you can tell the difference.

How long after a faint positive should I test again?

Lincoln says that if you get a faint line on your test and it concerns you, test again in the coming days. "It's most accurate to wait until the day of when you'd expect your period to come, but with the sensitivity of our tests it is OK to start testing a few days prior."

If an at-home pregnancy test is positive, "the majority of people don't need a blood pregnancy test to confirm they are pregnant. And in fact, our[doctors'] urine tests are exactly the same as the ones you can buy yourself so no need to come in for those either," says Lincoln.

There are some circumstances where a blood test might be needed: "If your healthcare provider is concerned about an ectopic pregnancy or miscarriage, or you are undergoing fertility treatments, a blood test may be recommended, but other than that they aren't usually needed."

Insider's takeaway

If you take an at-home pregnancy test correctly and see a faint line, it either means you are pregnant or have recently been pregnant and miscarried.

The best time to test for a pregnancy is the day you would expect your period to come.