Can an ovulation test detect early pregnancy?

Written by: Dr. Amy Beckley, PhD, Founder and Inventor of the Proov test the first and only FDA-cleared test to confirm successful ovulation at home.

Written on 4/14/21

can an ovulation test detect early pregnancy

Some women claim ovulation tests may be able to detect early pregnancy. Keep reading to learn if this is true!

Ovulation tests are helpful tools when trying to conceive, as they can give you insight into your fertile window — the days during your cycle when you’re most likely to conceive.

However, some women claim ovulation tests may be able to detect early pregnancy. Is this true? Keep reading to find out!

What are ovulation tests?

Ovulation tests (also called LH tests) are urine-based hormone tests that detect changes in luteinizing hormone (LH) levels to predict when ovulation is going to occur. LH is the hormone that surges about 24-36 hours before ovulation in order to trigger the ovary to release the egg.

Ovulation tests may be either thin simple urine strips or digital-based tests.

Urine-based tests — like Proov Predict — have a control line that will instantly turn pink in contact with your urine, proof that the test is valid. The second line is the test line; the intensity or darkness of the test line depends on the amount of LH present in your urine.

We always have a little bit of LH in our bodies, regardless of where we are in our cycle, so it’s not unusual to get a faint pink second line on your strip. This doesn’t mean the test is positive! For an ovulation test to be positive, the test line must be as dark or darker than the control line. A test with two identical lines indicates the beginning of the LH surge and that ovulation is approaching.

Digital ovulation tests, on the other hand, use smileys instead of lines to indicate LH levels. When your levels of LH are really low, you will get an empty circle indicating the test is negative. As your follicles grow and estrogen slowly starts increasing, you may start getting a flashing smiley face, indicating you are approaching the surge. These tests are considered positive (meaning LH is surging) when there is a solid smiley face.

Why should I use ovulation tests?

Ovulation tests are most commonly used when trying to conceive, in order to time intercourse so that you increase your chances of conception. As you may know, there are only a few days each cycle when you can successfully conceive.

These days are referred to as your “fertile window” and they are the few days leading up to and the day of ovulation. A positive ovulation test indicates the opening of your fertile window.

can an ovulation test detect early pregnancy

A positive ovulation test indicates the opening of your fertile window.

When do I use an ovulation test?

If you are using Proov Predict, we recommend beginning to test LH levels about 18 days before your next suspected period. If your cycles are irregular or if it is your first time testing, you may start using your LH tests a few days after the last day of your period. If you’re not using Proov Predict, we recommend reading the instructions for your specific ovulation test brand, as protocols can vary.

LH surges in blood very early in the morning and then needs another couple of hours to show in urine. 

This is why testing with second morning urine, usually around noon after a few hours hold, can be more accurate than testing with first morning urine. Luckily though, we include plenty of LH tests in our Proov Predict kits so that you can test levels two times per day!

Once you get your first positive ovulation test, this is considered your “peak” day. Ovulation usually occurs 12 to 36 hours post surge but some women may ovulate a bit earlier and others a bit later.

One thing to keep in mind though: it sometimes happens that an LH surge doesn’t end up in ovulation, your body may gear up to release the egg but the surge may not actually result in ovulation. This is why confirming ovulation is so important!

Can an ovulation test detect early pregnancy?

Although they both have two lines and use urine, ovulation and pregnancy tests are not the same. As we know, ovulation tests measure LH in urine to predict ovulation. Pregnancy tests, on the other hand, measure human chorionic gonadotropin (hCG) to confirm pregnancy.

Yet, you may have heard some women claim that an ovulation test can detect early pregnancy. How could this even happen?

It’s all thanks to chemistry!

Both LH and hCG are proteins that are built with a sugar attached to them. Their functions are completely different, with LH triggering ovulation and hCG maintaining pregnancy. Yet their structures are very similar!

So similar that some ovulation tests aren’t sensitive enough to tell the difference between LH and hCG in urine. While it is unlikely for a woman to use an ovulation test at the end of her luteal phase when she is well past peak fertility, some do and — if they’re pregnant — can get a positive result.

can an ovulation test detect early pregnancy

LH and hCG’s structures are so similar that some ovulation tests aren’t sensitive enough to tell the difference between the two in urine.

Why should I use a pregnancy test instead of an ovulation test?

Although some ovulation tests may be able to detect pregnancy, we recommend sticking with each test’s indicated use: ovulation tests for predicting ovulation and pregnancy tests for confirming pregnancy.

As we mentioned, pregnancy tests detect hCG, which is only produced by the placenta after you’ve successfully conceived. The presence of hCG confirms, without a doubt, that you are in fact pregnant.

An LH test on the other hand may occasionally turn positive in early pregnancy could be misleading as some women just have high LH levels throughout their cycle. Some women even get a second LH surge just before their period, so an ovulation test could be detecting this instead of pregnancy. To be confident in your test results, we recommend using each test as directed!

How soon can a pregnancy test detect early pregnancy?

Implantation can occur anytime between days 6 through 12 after ovulation. Studies actually show that the most common implantation day is day 9 post ovulation. Once implantation occurs, it can take about 24 hours for hCG to show up in your urine.

So while some home pregnancy tests claim to detect early pregnancy, they technically cannot detect hCG until it appears in urine. If we’re following the above guidelines, this could be as early as day 7 post ovulation or, more likely, day 10 post ovulation.

This is something to keep in mind since if you test too early, you’re more likely to get a negative result and count yourself out that cycle when, in reality, the embryo could have implanted later!

While the science behind using an ovulation test as a pregnancy test is super cool, we still recommend using each test for what they’re meant to do. Both are important on your TTC journey!

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“Hormone balance plays a huge role in fertility, and understanding what’s going on with your hormones doesn’t have to be such a mystery.

It’s actually way easier than most people realize.” 

— Amy Beckley, Proov Founder