Will an ovulation test be positive if you're pregnant?

We're here to help set the record straight! Below you'll find everything you need to know about how different types of tests work, will an ovulation test be positive if you're pregnant, what's the difference between an ovulation test and a pregnancy test, and how to read tests to understand the results.

How do ovulation tests work?

At-home ovulation tests, sometimes called LH tests or OPKs (Ovulation Prediction Kits), measure the levels of luteinizing hormone (LH) in urine. These tests can help determine whether ovulation is likely to occur or is occurring [1].

LH is a key hormone that plays an important role in male and female reproductive health [4]. LH levels fluctuate throughout the menstrual cycle, just like the levels of other sex hormones like estrogen and progesterone.

Because LH plays a key role in the release of a female egg cell [4], there's a surge in the levels of LH right around the time we ovulate–usually 24-48 hours before ovulation [5]. The ovulation test will show a positive result when there's a significantn increase in the LH.

Can an ovulation test detect early pregnancy?

The short answer to this question is: it's complicated.

Technically, an ovulation test can detect an early pregnancy because the LH and hCG hormones are molecularly similar [3]. So, if you're pregnant at the time of taking an ovulation test, the high levels of hCG may register as LH levels and show a positive result.

Despite that, an ovulation test is not designed to detect pregnancy, so it's not an accurate way to confirm a pregnancy. A positive ovulation test doesn't mean you're pregnant — it's a sign that the LH levels in your body have increased, which can be caused by many factors, such as ovulation [6]. 

If you suspect you may be pregnant, opt for taking an at-home pregnancy test (not an ovulation test) on the first day of your missed period. If you get a positive result from the pregnancy test, it’s time to book an appointment to confirm the pregnancy and discuss the next steps with your healthcare provider.

Reasons you might want to use an ovulation test

You may be wondering why bother with taking an ovulation test. Well, there are a few reasons why you'd want to know when you’re going to ovulate:

• When planning a pregnancy: Taking an ovulation test can help you find your fertile window so you know when is the best time to have sex to increase your chances of conception. 
• When trying to prevent pregnancy: Ovulation tests can also be used as a tool to find the fertile window in order to prevent pregnancy. They can be used alongside fertility awareness methods, or with the temperature-based FDA Cleared birth control app Natural Cycles. 
• Learning more about your cycle: As well as helping you achieve certain fertility goals, knowing your LH levels can also bring enhanced knowledge about your body and wider reproductive health. Once you know you’re going to ovulate, you might notice other signs of ovulation, such as increased cervical mucus or a high sex drive. It can also help you monitor cycle conditions such as polycystic ovary syndrome (PCOS). 

Pregnancy tests vs. ovulation tests

One thing that both at-home pregnancy and at-home ovulation tests have in common is that both require you to pee in a cup and dip the strip in the urine (in many cases). The main difference between pregnancy and ovulation tests is the hormones they are designed to detect in urine and blood.  

At-home pregnancy tests are designed to detect the presence of the hormone hCG (human Chorionic Gonadotropin), which is present in urine only when we're pregnant [2]. However, there are certain rare cases when this hormone may be present in both blood and urine, even if we're not pregnant. For example, this can happen when taking certain fertility medication [7].

At-home ovulation tests detect a different hormone–luteinizing hormone (LH). LH is present in our blood and urine at all times, but its levels fluctuate—they're often lower at the start of the cycle and peak right around ovulation [8]. Typically, an ovulation test shows up as positive during the peak in LH levels.

Positive ovulation tests while pregnant

You may see a positive result on your ovulation test if you’re pregnant. A positive ovulation test while you’re pregnant doesn’t mean you’re ovulating. Sometimes, during pregnancy, an ovulation test may interpret high levels of hCG in urine as high levels of LH instead. This is due to both hormones being molecularly similar [3]. 

The chances of ovulation occurring when you're already pregnant are extremely low. This is known as superfetation, when ovulation, fertilization, and implantation happen even though another fetus is already present in the body. Research has described less than twenty cases of superfetation [9]. That's how rare it is, and in many cases, it happened during pregnancies that occurred after fertility treatment.

So, if you're pregnant and get a positive ovulation test result, there is a very high chance it's due to high levels of hCG rather than an ovulation happening.

Faint line on an ovulation test

There is no such thing as a faint positive result when it comes to ovulation tests. A faint line on an ovulation test does not count as a positive result. In fact it means it’s unlikely that ovulation will happen in the next 1-2 days. It could also mean that you have already ovulated, but the test wasn’t taken during the LH surge [10]. For an ovulation test to be considered positive, both lines should show equally strong. If you test and one line is slightly fainter than the other, it’s best to wait a couple of hours and test again. 

Remember that ovulation tests cannot confirm whether ovulation is or isn’t happening. These tests are simply an indicator of hormone levels in the body that have the potential to trigger the ovulation process. LH is always present in our bodies, and the levels fluctuate depending on what part of our cycle we're in. That's why you may see a faint line on the ovulation test as it detects the presence of even very low levels of LH in urine.

When should you take ovulation tests and pregnancy tests?

There’s an optimal time in the cycle to take an ovulation test and another time when it’s optimal to take a pregnancy test. Ovulation tests should be taken after your period in the days leading up to ovulation, during the follicular phase of the cycle. 

Ovulation can move around, and the surge usually occurs 24-48 hours before ovulation, so it’s important to begin testing a couple of days before you expect to ovulate. Whereas testing for pregnancy should come later, in the second half of the cycle, around the time you’d normally expect your period to arrive. 

When trying to conceive, it's normal to feel eager to find out whether or not you’re pregnant as soon as possible. While it's hard to remain patient when we're excited or anxious about the outcome, waiting for the right time to take the pregnancy test can save you time, money, and anxiety.

"Since hCG levels rise as the pregnancy is implanting, taking a pregnancy test too early can result in a negative result. This is why we recommend you take a test once you have missed your expected period," Dr. Natalie Crawford told Natural Cycles.

Knowing the best time to take these tests can be daunting, but don’t worry! You don’t have to do all the diary work on your own. The Natural Cycles app prompts you on the best day to take ovulation tests and pregnancy tests based on your unique cycle data. 

How do you know whether you're ovulating or pregnant?

What goes on in our bodies can sometimes seem magical or mysterious, underneath the surface hormones regulate processes like ovulation and pregnancy. However, these processes can be quite hidden, unless you know what to look for — and even then they’re often open to interpretation.  

Let's discuss what signs to look out for when you're trying to find out if you're ovulating or whether you're pregnant:

Ovulation signs

Aside from the ovulation test showing a positive result, here are other ovulation signs you can look for that indicate ovulation is approaching:

• Changes in cervical mucus: Right before ovulation, cervical mucus often becomes egg white, clear, thinner, and stretchy, which is a sign that ovulation is likely approaching [11].
• Increased sex drive: Some research suggests that some people experience a higher sex drive around the time of ovulation [12].
• Elevated energy levels and mood: Due to an increase in the hormone estrogen before ovulation, some people may feel high-energy and much more inclined to socialize and generally take on new challenges during this time [13].  
• Heightened sensitivity: Some people may experience their sense of smell heightening during the fertile phase of their menstrual cycle [14], and some may notice that they're much more sensitive to pain, in areas like the abdomen and lower back, which could be influenced by hormonal changes during different phases of the menstrual cycle [15].
• Higher body temperature: Our basal body temperature typically rises after ovulation due to increased levels of progesterone, and it generally stays elevated until just before the start of the period. Measuring the basal body temperature can help determine if ovulation has occurred [16].

Early pregnancy signs

The late period is probably the most popular and well-known sign of pregnancy [17]. However, it's not a universal sign, as some people may still bleed during early pregnancy.

The good news is there are other early pregnancy symptoms to look out for. "These symptoms can include nausea, lack of appetite, sensitivity to smell, food aversions, enlarged and/or tender breasts, bloating, and fatigue," explains Dr. Natalie Crawford.

Keep in mind that not everyone will experience pregnancy symptoms the same. Relying on symptoms alone is not a reliable way to detect pregnancy, as some of these symptoms are also associated with PMS or certain cycle conditions. 

If you are experiencing pregnancy symptoms or are getting a negative result on an at-home pregnancy test and your period still hasn’t arrived, it’s a good idea to talk to your doctor, who can test for HCG in your blood.

Know when you ovulate with Natural Cycles

Natural Cycles is an FDA-cleared birth control app that uses your biometric data, including temperature and optional ovulation tests to help you find your fertile days so you can plan or prevent pregnancy hormone-free. Natural Cycles has partnered with at-home testing experts Clearblue to make at-home ovulation testing as seamless as possible. The NC° app will prompt you on the best day to take an ovulation test, log the result and our algorithm will calculate your fertility status. Whatever your fertility goal, why not find out how Natural Cycles can support you?