There are a lot of different tests out there promising to let you know if you’re pregnant—but which is the best pregnancy test? That depends on what you mean by “best.”
For most women, the best pregnancy test is the most sensitive—the one with the lowest threshold for detecting the pregnancy hormone hCG. (The more sensitive a pregnancy test is to hCG, the earlier it will be able to detect a pregnancy.)
Also important: The data used in pregnancy test product reviews. More specifically, where it comes from. (i.e., Is it the review using data from the manufacturer of the test, or from an independent study?)
Things to look out for:
- Most product reviews you read on pregnancy tests will simply give you the manufacturer’s data about the test.
- Manufacturer’s data about the sensitivity of tests varies from the data that comes from independent studies.
- Manual pregnancy tests are faster and usually more accurate (the digital ones are sometimes prone to errors). In fact, the digital tests use the exact same sensors to detect your level of hCG—but the digital ones use a sensor to read the results (thus you wait longer for the result, usually about a minute).
What is the most sensitive pregnancy test?
Our pick? The First Response Early Results test. According to an independent study, it has an analytical sensitivity of 6.3 mIU/mL. It’s estimated to detect greater than 95% of pregnancies on the day of missed period, gives you fast results, and is more reliable than the at-home digital tests (which can sometimes be faulty).
How early can I detect pregnancy?
While most doctors recommend that you wait until the first day of your missed period to accurately detect pregnancy, if you understand the timing of your own menstrual cycle, you can get an accurate pregnancy test result several days earlier.
How early you can detect pregnancy depends on three variables:
1. When implantation occurs
Pregnancy tests detect the presence of the hormone hCG, which is produced by the embryo after implantation. Implantation can happen anywhere from 6 – 12 days after ovulation/conception, but most of the time it happens 8 – 10 days after ovulation. Once implantation is complete, hCG levels will double roughly every 48 hours. So part of the answer to how soon you can get a positive pregnancy test depends on when implantation occurs.
2. Your baseline hCG levels
The other part of the answer depends on your baseline hCG levels. Even when you are not pregnant, you have a very small amount of hCG in your body—up to 5 mIU/ml. If you have a higher baseline level of hCG than your friend, and you are both pregnant, and you both had implantation happen on the same day, you may be able to get a positive pregnancy test earlier than she can, since hCG doubling time includes your body’s baseline hCG, so you have a bit of a head start!
3. Your hCG doubling time
The final variable is hCG doubling time. While hCG levels double on average every 48 hours, this figure can vary from woman to woman. If your hCG doubling time is on the slower side, it will take a little longer until you have enough hCG in your body to get a positive pregnancy test.
Based on all three of these variables, you can see that it’s highly unlikely to get a positive pregnancy test before 9 – 10 DPO (days after ovulation), and most women probably won’t test positive until 11 – 12 days after ovulation. (Read more about when to take a pregnancy test.)
What’s the best early pregnancy test?
If you’re testing on the first day of a missed period, it doesn’t matter very much which test you use—most currently marketed tests are reliable and will yield a positive result for 98 percent of pregnant women. But if you’re testing earlier than your missed period, you should use a more sensitive test.
Note that we don’t necessarily recommend testing early, just that if you are going to test early, you should use a sensitive pregnancy test. The more sensitive your test is to hCG, the earlier you will be able to get a positive result.
(Keep in mind that if you test early, you may get only a very faint line on your pregnancy test)
Most pregnancy test brands claim an hCG detection threshold range anywhere from 6.3 – 50 mIU/ml, with most tests falling between 20 – 35 mIU/ml. However, test manufacturers claims are not verified by independent testing. When independent studies have been carried out, the results are often quite different from what the test manufacturers claim. Some websites claim to list the sensitivity of various pregnancy test brands, but these sensitivity claims usually come directly from the test manufacturer rather from an independent testing agency.
A few independent studies have been done to test the sensitivity of various pregnancy test brands. Based on these studies, hCG threshold data for a few common pregnancy test brands are available:
- Clearblue (manual and digital tests): 22 mIU/ml
- e.p.t. (manual and digital tests): 22 mIU/ml
- First Response Early Results: 6.3 mIU/ml
What other factors should you look for in a pregnancy test?
Ease of use
Pregnancy test brands differ in how easy they are to use. Mid-stream tests require that you hold the test directly into your stream of urine, while dip-stick tests require you to pee in a cup, then dip the test in for a few seconds. Many women prefer the dip-stick tests because they are less messy, but this is a matter of personal preference.
Price
If you’re the kind of woman who prefers to wait until your period is several days late and you’re already experiencing early signs of pregnancy such as sore breasts or increased sense of smell, price probably isn’t the most important factor to you in evaluating pregnancy tests.
But if your habit is to take lots of pregnancy tests during the two-week wait, it makes sense to look for cheap bulk pregnancy tests, usually purchased online (try brands like Wondfo or Easy at Home).
Clarity of results
After the wait time has passed, you look into the results window to determine whether the test is positive or negative. Positive tests carry a plus sign, two lines, or an explicit message such as “yes” or “pregnant.”
Some women prefer the tests that say “yes” or “pregnant” because there is no gray area in interpreting the results.
Other women prefer the two-line tests because the second line is directly correlated to the concentration of hCG in the urine (hCG is the hormone that an embryo produces after implantation). The darker the second line, the higher the concentration of hCG. It can be reassuring to see the line getting darker over several days as hCG levels increase in early pregnancy.
The downside of two line tests is that the results can sometimes be difficult to interpret. Any second line—even very faint—indicates a positive result. However, if the tests are not used properly, a false second line can sometimes appear (learn how to tell the difference between a positive pregnancy test and a false positive).
Why should you trust us?
I’m a science writer, with a decade of experience in journalism—interpreting clinical studies, research papers for outlets like The New York Times and The Washington Post. But perhaps most important: I’ve had two children. So, I understand the critical importance of discriminating fact from fiction when it comes to fertility and pregnancy. (The truth is: when it comes to fertility and pregnancy, there are a lot of false claims, misleading information, and lingering myths out there.)
Here at Ava, we take data—especially fertility and pregnancy data—very seriously. Our mission is to give women impeccable data about their reproductive health. Our team is led by premier data scientists, obstetricians, gynecologists, and reproductive endocrinologists, many of whom hold Ph.D.’s and decades of experience in their respective fields. So, when you read content on AvaWorld, you can trust that it’s backed by science and has been thoroughly researched and vetted by our experts.
By Lindsay Meisel |
Tags: chemical pregnancy, early pregnancy, early pregnancy symptoms, implantation, miscarriage, pregnancy, pregnancy tests, trying to conceive, two week wait
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Sensitivity of over-the-counter pregnancy tests: comparison of utility and marketing messages.
Lindsay Meisel
Lindsay Meisel is the Head of Content at Ava. She has over a decade of experience writing about science, technology, and health, with a focus on women's health and the menstrual cycle.Her work has been featured on The Fertility Hour, The Birth Hour, The Breakthrough Journal, and The Rumpus.