Light positive pregnancy test at 4 weeks

If your second pregnancy test result is lighter than the first one you took one or two days before, you may be confused. This guide will walk you through what could be causing a pregnancy test to get lighter. 

By OBGYN and fertility expert Dr. Kenosha Gleaton

The home pregnancy test has been a game changer for women. Before they were widely available at your local Target (and online!), women had to go to the doctor and get a blood test to confirm a pregnancy. Now that we can take these amazing tests in the privacy of our own home, you may run into issues or have questions about the results. Don’t worry, we’re here to help! Today, let’s discuss what to do if your test result looks lighter today than it did previously. 

Should pregnancy test lines get darker?

In general, yes, pregnancy test results should get darker early on as a pregnancy progresses. This is because the pregnancy hormone, hCG, typically doubles every two to three days during the first few weeks of pregnancy. After six weeks, the levels will double about every four days. And towards the due date, hCG levels actually decrease.

If you are taking a pregnancy test before the day of your expected period, and are indeed pregnant, the line will start as a faint line (a “squinter”) and get darker as time progresses. 

Reasons why a pregnancy test could be getting lighter

With home pregnancy tests, you’re likely to have questions about interpreting results as opposed to pregnancy tests done at your doctor’s office. One of these questions with a home pregnancy test is a light or faint line. Two lines on our pregnancy test, no matter how faint, is a positive result. But say you tested today and the line seems lighter than your test from yesterday—don’t panic. It could simply be that your urine was more diluted today, meaning it was harder for the test to detect the hCG. Test again in the morning when the hCG should be most concentrated.

If you tested today and the line seems lighter than your test from yesterday. Don’t panic. It could simply be that your urine was more diluted.

If you test again over a few days or weeks and the line continues to get lighter or disappears, a couple of things could be happening:

• If you tested with two brands that have varying levels of sensitivity, the results could look different. Try using the same brand test and comparing tests within the same brands.
• The first result could have actually been an evaporation line, which is extremely frustrating. Learn more about the difference between evaporation lines and faint positives. 

• It could be a chemical pregnancy. A chemical pregnancy is a very early miscarriage that occurs when an egg is fertilized, but does not fully implant into the uterus.

What if my pregnancy test got lighter, but still no bleeding?

If you’ve missed a period and received a positive test result, but the next test is lighter, it could be due to any of those things listed above. If your period usually comes like clockwork and you still don’t see Aunt Flow in a week, take another test (ideally in the morning). Of course, you should reach out to your doctor if you have any concerns. 

What if I got a positive pregnancy test followed by my period? 

It’s important to differentiate if it is your period or spotting.

Spotting after a positive pregnancy test occurs in 15-20% of pregnancies in the first trimester.

Spotting (aka implantation bleeding) is much lighter than most periods and lasts for a day or two. Spotting happens when the fertilized egg causes a little bit of lining to detach during implantation and is an early sign of pregnancy.

Getting your full period after a positive pregnancy test, on the other hand, could potentially be a chemical pregnancy. A chemical pregnancy is a very early miscarriage that occurs when an egg is fertilized but does not fully implant into the uterus. The bleeding associated with a chemical pregnancy is typically like a period, but can be heavier. If you test again and the result is negative, this could be the case. If you are having a chemical pregnancy, keep this in mind: research shows that women may be more fertile following a chemical pregnancy.

If you are having a chemical pregnancy, keep this in mind: research shows that women may be more fertile following a chemical pregnancy. 

Learn more about chemical pregnancies. 

Ectopic Pregnancies

It is rare, but bleeding in early pregnancy that is heavier and/or accompanied by abdominal pain may indicate an ectopic pregnancy.

This is when an egg implants outside of the uterus, which can be life-threatening for a pregnant woman. In the case of ectopic pregnancy, hCG levels may be lower and/or rise abnormally. If the home pregnancy test is positive, but you suspect it could be an ectopic pregnancy, you will need to see your provider immediately for further blood testing or ultrasound to make the diagnosis.

Getting pregnant can be a difficult and confusing process. We at Natalist are here to serve you during this time. Please don't hesitate to reach out if you have any questions.

What does an immediate dark positive pregnancy test result mean?

While it has been rumored that an immediate dark positive pregnancy test means twins, this is not necessarily the case, and there are other reasons why this could happen. An immediate dark positive result could mean that there's a high concentration of hCG in your urine, and the test is showing an immediate dark result due to the level of hCG. One thing to note is that all home pregnancy tests are different and may detect hCG at different levels. The Natalist Pregnancy Test detects hCG with high sensitivity at 10 mIU/mL hCG.

When trying to get pregnant, it also helps to keep track of your menstrual cycle and ovulation. Understanding how often and when to have sex during ovulation can greatly increase your chances of pregnancy. An ovulation test can also be helpful in determining when ovulation happens so you can plan intercourse accordingly. 

The bottom line is if you notice a missed period and/or end up taking an at-home pregnancy test, keep in mind that both faint positive lines and immediate dark lines are possible. If you are concerned about your test results, it may help to track any pregnancy-like symptoms you may be experiencing and check with your doctor about questions. 

Take-aways:

• Pregnancy test results should get darker early on as a pregnancy progresses.
• If your pregnancy test results seem to be getting lighter, it could be because you tested after drinking water and your urine was more diluted. Or, the first test result could have been an evaporation line and not a positive result. Test again in the morning.
• Test results can also look different if you are comparing results of two different brands of tests. We recommend sticking to one type of test when testing early on and comparing results over time. 
• A positive pregnancy test followed by light bleeding could be spotting, a sign of implantation.
• A positive pregnancy test followed by your period (and a negative test) could be a chemical pregnancy. These early pregnancy losses don't usually require medical intervention, but you should let your doctor know. 

• Symptoms of an ectopic pregnancy can be abnormal vaginal bleeding, low back pain, and pain in the abdomen or pelvis. If you have abnormal bleeding and pelvic pain, talk to your doctor immediately. 

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