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You took a pregnancy test, saw those two pink lines, and have been giddy ever since. But now the test line’s getting lighter and you’re starting to worry.
Sound familiar? We feel you. Pregnancy test progression can be an emotional roller coaster.
So how do you know your test line is progressing normally? And what could get in the way of your line getting darker?
Let’s clear things up. Keep reading to learn what a normal pregnancy test line progression looks like. But first, let’s cover some basics.
How do pregnancy tests work?
Pregnancy tests detect hCG or human chorionic gonadotropin in your blood or urine. Your body only makes hCG during pregnancy. So, when it shows up, it’s a surefire sign you’re pregnant.
hCG blood tests require a doctor’s visit. Because of this, most women take at-home urine tests. The good news? Both tests are 99% accurate when used correctly. So there isn’t a significant difference between the two.
Like ovulation tests, most pregnancy tests come with two lines: a control line and a test line. The control line means the test is working. The test line delivers your results.
A positive pregnancy test is when the test line shows up, no matter how light or dark. The darker the line is, the higher your levels of hCG.
Tests vary in their sensitivity. But most need 20-25 mIU/mL of hCG to deliver a big fat positive.
That’s why it’s best to hold off taking pregnancy tests until the first day of your missed period so that your hCG levels have time to build.
If your results are unclear but your body is sending signals that you’re pregnant, you may have tested too soon. In this case, take a break for a week to let your hCG levels grow and then retest.
What is a normal pregnancy test line progression?
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.’ It tapers off as you progress into your pregnancy.
At about 10-11 weeks of gestation, hCG hits its peak. From there, it stays steady or starts to drop.
This means if you’re testing regularly, the test lines should get darker until you reach the 10th week of pregnancy. After that, the lines may look the same or lighten up.
Know more: hCG Doubling in Pregnancy: Why It Matters
Why is my line not progressing?
If you’ve been testing often and the line looks faint or isn’t as dark as you expected, try not to panic. There could be a very simple explanation.
Here are a few things that can affect line progression on pregnancy tests:
Reason #1: You’ve got “line eyes”
Your eyes could be playing tricks on you. Reading lines on pregnancy tests is a bit like reading poetry. Everyone interprets it differently. One easy way to bypass this is to ask someone else to interpret your test results. Sometimes it helps to have another set of eyes. Or consider taking a digital test. These display a simple ‘pregnant’ or ‘not pregnant’ so there’s no guesswork.
Here’s what some of our users had to say:
Reason #2: Your urine is diluted
The more water you drink, the more hCG gets diluted in your pee. If you take a test and the line looks faint, you could just be more hydrated that day. One simple way to avoid this is to test with your first-morning urine.
Reason #3: Your test is expired
You can’t trust the results of expired tests. So if a test is expired, toss it and retest.
Reason #4: You’re mixing brands
As mentioned, different brands have different levels of sensitivity. This can make it hard to compare the results if you mix brands. For the most accurate results, it’s best to stick with the same brand.
Reason #5: You’re testing past 6 weeks
The hCG doubling rate slows down at around 6-7 weeks of pregnancy. If you take a test past this point, the line won’t progress as quickly. So you have two options. You can either:
- Stop testing past 6 weeks altogether.
- Know the test line may get lighter after 6 weeks–and that’s normal!
Why is my test line not getting darker?
Apart from the things we just covered, there could be a few culprits:
Evaporation line
If a pregnancy test sits for too long, you may end up with an evaporation line. Once your pee evaporates, the salts from your urine stay on the strip. This can create what looks like a faint line–but it’s not a true positive result.
If you spot an evaporation line, you likely waited too long to read the test. In this case, discard the test and try again with a fresh one.
Know more: What is an Evaporation Line on a Pregnancy Test?
Early pregnancy loss
Sadly, sometimes if a line isn’t getting darker, it could be a sign of an impending miscarriage. One study found that women with slow-rising hCG levels have a higher risk of pregnancy loss.
If you have concerns about how your test line is progressing, you may want to give your doctor a heads-up. It doesn’t hurt to be on the safe side.
Ectopic pregnancy
While rare, this is when the fertilized egg implants outside the uterus. hCG levels still rise in ectopic pregnancies, but not as much. This can make the test line not darken as quickly.
Ectopic pregnancies can become dangerous if left untreated and need prompt attention. If you have any signs of an ectopic pregnancy like abdominal pain or heavy bleeding, see your health care provider right away.
Why is my test line getting lighter?
If your test line fades or disappears altogether, a couple of things could be at play:
The ‘hook’ effect
If hCG levels get too high, it can overwhelm the test and cause a false negative. This phenomenon is known as the ‘hook effect.’ While rare, it’s seen most often with twins, triplets, or anything that sends hCG levels over 500,000 mIU/mL.
When the test gets oversaturated, it can’t bond properly with the hCG molecules. This may lead to a false negative result. hCG levels peak around the 10th or 11th week of pregnancy. So if you’re testing around then, be sure to keep this in mind.
Chemical pregnancy
This is a very early miscarriage that happens before the fifth week of pregnancy. The egg gets fertilized, but something goes wrong during implantation. This causes hCG levels to drop.
If you get a positive pregnancy test, but it starts to fade or goes negative soon after, it could be a chemical pregnancy.
Chemical pregnancies are NOT your fault. They’re usually due to chromosomal abnormalities that would affect the fetus’s development. But that doesn’t diminish how heartbreaking they can be. If you could use some support on your fertility journey, your Inito community is here for you.
Tips to ensure proper test line progression
Taking pregnancy tests can be exciting, but also anxiety-inducing. So here’s a handy cheat sheet to help your testing go as smoothly and accurately as possible:
Tip | How does it help? |
Follow the instructions carefully and check the result in the suggested timeframe. | Prevents evaporation lines |
Check the expiration date and don’t use expired tests. | Prevents skewed results due to expired tests. |
Get another person to interpret your test results. | Helps avoid “line eyes” |
If you retest after getting a positive result, stick with the same brand | Different brands have different sensitivities. If you mix brands, it could affect your results |
Test with first-morning urine and avoid drinking too much water before testing. | Prevents diluted urine which can reduce hCG’s concentration in your pee |
Takeaways
- Pregnancy tests detect hCG in your urine, a hormone that’s only made during pregnancy.
- When a test detects hCG, the test line darkens. This is considered a positive pregnancy test.
- hCG doubles approximately every 2 days in the first few weeks of early pregnancy. This can make the test line get darker if you retest.
- At the 10-week mark, hCG peaks. From there, levels hold steady or begin dropping. This can make the test line fade.
- Many things can get in the way of pregnancy line progression. Using expired tests, mixing brands, and drinking too much water before testing are a few.
- If you wait too long to read a pregnancy test, it can create a faint line that looks like a positive result. This is known as an evaporation line, but it’s not a valid result.
- Chemical pregnancies and ectopic pregnancies can also interfere with pregnancy test line progression.
- Always test with your first-morning urine to prevent inaccurate results and read the test within the right timeframe.
FAQs
It depends on the test and your hCG levels. Most tests can detect 20-25 mIU/mL of hCG. Early pregnancy tests are more sensitive and claim they can detect hCG as soon as 8 days before ovulation. That said, your best bet to prevent a false negative is to wait until the first day of your missed period.
The hCG doubling time slows down after 6-7 weeks of pregnancy. If you take a test beyond this, the line won’t progress as expected. So you can stop testing once you reach the 7-week mark.
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- hCG (Urine) – Health Encyclopedia – University of Rochester Medical Center
- Strips of Hope: Accuracy of Home Pregnancy Tests and New Developments – PMC
- Chorionic Gonadotropin Beta Subunit – an overview | ScienceDirect Topics
- Doubling times of human chorionic gonadotropin increase in early viable intrauterine pregnancies
- Poor prognosis for successful pregnancy with slow-rising beta-human chorionic gonadotropin (hCG) levels even with fetal viability at eight weeks. – Fertility and Sterility
- Diagnosis and treatment of ectopic pregnancy – PMC
- Screening Method to Evaluate Point-of-Care Human Chorionic Gonadotropin (hCG) Devices for Susceptibility to the Hook Effect by hCG β Core Fragment: Evaluation of 11 Devices | Clinical Chemistry | Oxford Academic
