Yes, a faint positive line on a pregnancy test should get darker over time (a few days) as hCG levels rise in early pregnancy, but a line that appears or darkens only as the test dries (after the time window) is likely an evaporation line, which is colorless and misleading. A true faint positive has color (pink/blue) within the 3-10 minute window and indicates low hCG, meaning you should retest in 48-72 hours for a darker line if pregnant.
Babatunde explains: “hCG levels double every 48-72 hours, so a faint line should become darker over time. However, if it fades, it might be a chemical pregnancy, a common early miscarriage. If you're worried about the reliability of blue dye tests, use pink dye tests or digital tests for clarity.
When a liquid dries, you may notice the appearance of crystal-like streaks or faint lines. These faint streaks or lines can look like a positive result, although it's good to note that evaporation lines do not indicate pregnancy, nor are they related to hCG (human chorionic gonadotropin).
For the most part, the lines on a pregnancy test don't get darker as they dry. That's because how dark or faint they look depends on the level of hCG detected, not the amount of pee.
Seeing a faint line can leave you unsure. The first step is to wait 2 to 3 days and take a faint line retest. Hormone levels double every two days, so the line should get darker if you are pregnant.
If the faint line doesn't get darker over time or stays faint for several days, it could signal a chemical pregnancy—a very early pregnancy loss. This can be emotionally difficult and confusing. If you suspect this, contact your healthcare provider for a blood test to track hCG levels accurately.
Q2: Should I retest a few days after receiving a faint positive result? A: Rather, the majority of experts advise delaying testing for a few days—ideally, until a week after the first day of your missed period—before doing so.
If you leave the test out for too long before reading it, you may end up with what looks like a positive result. This might actually be an evaporation line, which is a faint, colorless line that appears in the test window when the urine dries.
How to distinguish from true positive results. Unlike a faint positive result, which will result in a light pink or blue line, an evaporation line does not activate the dye in the pregnancy test. This means that it may show up as a colorless or translucent line.
You always have a linea nigra, but it's nearly invisible until your hormones rise during pregnancy. In most people, the linea nigra darkens enough to be visible in the second trimester (around 20 weeks).
Consider the color of the line
“The difference between an evaporation line [and] a positive line is typically color. The evaporation line is usually a colorless line, while a faint positive line will have trace color,” Burroughs says.
“While there's no exact minimum hCG level required, it typically occurs when levels reach 500 to 1,000 mIU/mL or higher, depending on the sensitivity of the test,” explains Peña. “Since hCG rises rapidly in early pregnancy, some people may see a dye stealer as early as 21 to 28 days post-ovulation, but this varies.”
As a rule, pregnancy test lines should get darker as you get farther into your pregnancy. At least in early pregnancy, that is. That's because hCG levels double roughly every 2 days, the first 6-7 weeks you're pregnant. This is known as the 'hCG doubling time.
Some brands use blue dye in their pregnancy tests, so a strong positive might be a bright blue color, while a faint line might show up as light blue. Other brands and tests use red dye, so a strong positive might show up as a red line, while a faint line will appear as a light pink color.
In particular, read the test within the stated time as, beyond this point, it may no longer be accurate. This is because evaporation lines tend to manifest after the recommended reading time, usually within 10 minutes. A genuine positive line should appear more quickly within the specified timeframe.
A test line can be faint pink if your urine is diluted or it's very early in your pregnancy. Not-to-worry, though. Even a faintly pink-colored test line indicates a positive result. Simply put, if there is color on the test line, it's time to check in with your doctor to confirm a pregnancy.
If your line is getting darker, it's more likely to be either the control line (this is generally the darkest line on a pregnancy test) or a positive result. Evaporation lines on pregnancy tests usually get lighter as your pee evaporates.
Evaporation lines are colorless. Unlike the lines on your test, they don't have a dye. They won't be pink or blue like the control line. They may be a faint gray compared to the white on the test strip.
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 can look like a faint positive line, which is why it's important to follow the instructions on home pregnancy tests and set a timer to check the result.
A 2-hour urine hold pregnancy test is a helpful way to get a more accurate result by ensuring that your urine has enough of the pregnancy hormone, hCG, for the test to detect.
Your faint positive pregnancy test should be enough to know you are pregnant. However, if you prefer, you can wait a day or two to test again first thing in the morning and see if you receive another positive result. After a positive pregnancy test, your next step is to schedule an appointment to verify your pregnancy.
Home pregnancy test results are only accurate within the first 10 minutes, so read results promptly to avoid misleading lines.
It's best to schedule an appointment with a medical provider to confirm pregnancy test results around the eighth-week mark after a missed period. Some women may need to see a physician sooner if they experience any of the following symptoms. Pregnancy changes the body, starting from the moment of conception.