Will Ovulation Tests Be Positive if You’re Pregnant?

Originally published 09/07/2020. Updated for accuracy and relevancy on 02/18/2024

You may have heard that ovulation tests can be used to test for pregnancy. In this guide, we’ll walk through the somewhat complicated answer.

By Dr. Kenosha Gleaton

So can an ovulation test detect pregnancy? This isn’t a straightforward answer, so let’s talk through some of the considerations and variables.

Can Ovulation Tests Detect the Pregnancy Hormone, HCG?

The short answer is that ovulation tests can (sort of) act as a pregnancy test because the luteinizing hormone, LH, is molecularly very similar to hCG.¹ If you are pregnant, your human chorionic gonadotropin (hCG) levels will be much higher than normal and an ovulation test may inaccurately detect this and read it as a high LH level value. This is not to say that ovulation tests can substitute for a pregnancy test— pregnancy tests are much more accurate.

How Do Ovulation Tests Work?

Ovulation is an important part of a menstrual cycle and can help you track your fertile window when TTC. So when is ovulation exactly? During a regular menstrual cycle, ovulation occurs around day 14.² An ovulation test is a test that lets you predict when you are going to ovulate. This is important because eggs only live for a short time after they are released—24 hours max. If you’re trying to get pregnant, you want to figure out when to have sex during ovulation to optimize your chances of getting pregnant. Sperm are relatively hearty and can survive for five to six days inside the female reproductive tract, so if you have sex before ovulation, they’ll stick around waiting for their moment to act.

There are many different types of ovulation testings, but they work by the same basic mechanism: by detecting Luteinizing Hormone (LH) in your urine.³ Your brain makes the LH hormone to tell your ovaries it’s time to release an egg. LH levels in women surge about 12-24 hours before ovulation—conveniently when you're most likely to get pregnant. Many people have also calculated their due date based on ovulation.

How Do the Hormones LH and hCG Differ?

Both hCG and LH bind and function through a common hCG/LH receptor. The biggest difference between the two is that the hCG pregnancy hormone has a circulating half-life that is approximately 80-fold longer than that of LH.⁴ One study refers to hCG as a “super LH produced in pregnancy,” with 80 times the biological activity of LH.¹

Because the protein components of hCG and LH look very similar, an ovulation test is unable to distinguish between LH and hCG in your urine. Therefore, the right amount of either hormone in your urine will result in a positive OPK test result.

What Does an Ovulation Test Look Like If You’re Pregnant?

An ovulation test isn’t as sensitive as a home pregnancy test, so it won’t pick up hCG as early as a pregnancy test strip will, and it requires higher levels of hCG to turn positive. In addition, there is no way to distinguish whether the ovulation test strip is detecting your LH or HCG levels.

Can I Use Ovulation Tests to Test for Pregnancy?

We do not recommend using ovulation tests to determine if you’re pregnant, for several reasons:

• Ovulation kits are not as sensitive as pregnancy tests (25 mIU/mL vs 10 mIU/mL).
• It’s nearly impossible to determine if a positive ovulation test is from LH or hCG.

Therefore, you run the risk of a false negative result if it’s too early and a false positive result if it’s picking up LH. If you think you  have pregnancy symptoms, the best way to confirm with an accurate result is to use an early detection pregnancy test.

Natalist Is Here for You

Natalist offers a variety of high-quality products to support your health and wellness journey. Whether you're looking to support relaxation and bone health with Magnesium Powder , track your ovulation with an Ovulation Test Strips kit, or ensure optimal nutrition during pregnancy with Prenatal Gummies , we have everything you need to feel your best. Don't forget to utilize our fertility calculator for insights into your fertility window, taking a significant stride toward an even healthier and happier you. Plus, with our convenient online ordering and fast shipping, it's never been easier to prioritize your health.

Dr. Kenosha Gleaton is board-certified in gynecology and obstetrics and is the Medical Advisor of Natalist. She received her MD from MUSC and completed her residency at Carolinas Medical Center in Charlotte, NC.

Sources:

1. Cole LA. Biological functions of hCG and hCG-related molecules. Reproductive Biology and Endocrinology. 2010;8(1):102. doi:https://doi.org/10.1186/1477-7827-8-102
2. Ovulation signs: When is conception most likely? Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/getting-pregnant/expert-answers/ovulation-signs/faq-20058000
3. Su HW, Yi YC, Wei TY, Chang TC, Cheng CM. Detection of ovulation, a Review of Currently Available Methods. Bioengineering & Translational Medicine. 2017;2(3):238-246. doi:https://doi.org/10.1002/btm2.10058
4. Faiman C, Ryan RJ, Zwirek SJ, Rubin ME. Serum FSH and HCG during human pregnancy and puerperium. The Journal of Clinical Endocrinology and Metabolism. 1968;28(9):1323-1329. doi:https://doi.org/10.1210/jcem-28-9-1323