I didn’t even know this was “a thing” until I started perusing the forums. Yet another thing to stress and obsesses about, yay! A lot of women LOVE seeing their pregnancy test lines get darker and darker as they’re more and more days past ovulation (DPO).

As we explained here, home pregnancy tests, like First Response and Clearblue, detect hCG, the hormone produced by the placenta after implantation. Since hCG levels should double approximately every 48 hours, it makes sense that the pregnancy test line should get darker the further along one is.

As you can below, my test at 23 DPO is darker than my test at 17 DPO. Also, the test line turned pink almost immediately, whereas I spent about 5 minutes squinting at the other one.

However, this will no always be the case due to:

  • Who knows. I’ve read tons of posts on forums by women freaking out because their lines aren’t getting darker. Just Google my pregnancy tests aren’t getting darker and you’ll come across a myriad of stories. Some women get progressively darker lines, and some don’t, i.e. My lines stayed fairly faint until I was well into my pregnancy. I don’t have data, but if your lines aren’t getting darker, then try to not freak out too much and talk to your doctor as soon as possible. 🙂
  • Diluted urine. If you’re not using your first-morning urine, it’s possible that hCG levels are less concentrated. Even if you are using your first-morning urine, if you drank water late the night before, it’s possible that the hormone levels are less concentrated.
  • Not enough pee. It’s possible you didn’t get enough pee on the test to get a good result.
  • Test is a different brand, or a lemon. If you’re going to compare pregnancy tests, it’s important that you compare using the same brand! Not all brands have the same sensitivity and not all brands react identically. Make sure you’re comparing apples with apples. It’s also possible you got a lemon. I’ve taken numerous tests that were duds. If that’s the case, retest.
  • Test taken at a different time of day. Especially early on, time of day makes a big difference. If you take a test later in the day, it’s possible that the hormone levels are less concentrated, resulting in a fainter line.
  • Chemical pregnancy. A chemical pregnancy is a miscarriage that occurs before the fifth week of gestation. Chemical pregnancies take place before ultrasounds can detect a fetus, but not too early for a pregnancy test to detect levels of hCG.

A blood test is far more accurate than a urine test. I took a blood test shortly after getting my faint lines to be absolutely sure 🙂

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