Can an ovulation test detect pregnancy?

To help you understand your full fertility journey, we're getting to the bottom of ovulation tests.
Written by
Julia Hammond
Reviewed by
Dr Claudia Xiao
Last updated on
May 16, 2024
min read
Will an Ovulation Test Be Positive If You're Pregnant? | Kin Fertility
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Trying for a baby comes with many beautiful moments. There's the closeness you feel with your partner, the joy of regular intimacy and the excitement of everything the future holds. It's almost certain that your journey will involve a pregnancy test, but part of this journey may also involve ovulation testing.

Ovulation tests are not as well-known by many couples, but they can be useful when you're trying to get pregnant. As it turns out, there's an ideal fertile window that you don't want to miss for timed intercourse. The purpose of this test is to help you predict ovulation and make the most of your fertile days.

To help you understand your full fertility journey, we're getting to the bottom of ovulation tests — what they're for, how they work and why you might want to use one. We'll also answer the big mystery; can an ovulation test detect pregnancy?

The basics of ovulation

Before we get into all the details on ovulation tests — we thought a brief overview of ovulation might help.

Ovulation happens once per month, around 2 weeks before your period begins [4]. It’s the first natural step in your journey towards pregnancy where your body releases an egg, ready to be fertilised. Here’s what’s happening under the hood:

  • The first step happens in your brain. A hormone released by your pituitary gland tells the ovaries to start producing follicles.
  • These follicles begin to grow, releasing the hormone oestrogen in the process to thicken the walls of your uterus (ready for pregnancy).
  • Around day 7 of your cycle, all the follicles stop growing — except for one which now starts growing an egg.
  • Around day 12, this last follicle-standing releases a burst of oestrogen. This starts a growth spurt for the egg and kickstarts the production of an important substance called luteinising hormone (LH).
  • The last part happens rather fast. Your mature egg detaches itself from the follicle and launches into your fallopian tube, where it travels toward the uterus [1].

And that, friends, is the process of ovulation. To put it simply — it’s the growth and release of an egg from your ovaries that (fingers crossed) will be fertilised.

How long are you fertile?

Once an egg reaches your fallopian tube, it has 12-24 hours to have a meet-cute with sperm and be fertilised. If the egg is fertilised, you'll be in the early stages of pregnancy, But, if it reaches your uterus unfertilised, it's absorbed back into the body [1].

Fertility experts say that the best time to attempt pregnancy is in the 5 days leading up to ovulation, and the day of ovulation itself [4]. This is where ovulation predictor kits come in handy as predicting ovulation can help you identify when it's the best time to have sex.

How do ovulation tests work?

The purpose of an ovulation test is to tell you the time in your menstrual cycle that pregnancy is most likely [3]. They are sometimes referred to as an ovulation predictor kit (OPK) since they try to predict the exact timing of your fertility window.

How they work is quite simple. An ovulation test checks your urine for luteinising hormone (LH) surges. Your LH levels will be super high just as your body prepares to release an egg [3]. Most ovulation kits come with 5-7 ovulation test strips or sticks — giving you a few tries to find your peak fertility.

Ovulation tests are easy to read too, with only 2 lines to look at. The first is the control line, which tells you the test is working and gives you something to compare with. The second line is the test line — when it’s as dark or darker than the control, you have a positive OPK result [6].

Is it the same as fertility testing?

We feel it’s important to note that ovulation tests are not the same as detailed fertility testing. OPKs measure one thing and one thing only — luteinising hormone (LH) surges.

Does this mean they’re not useful? Not at all. In fact, their simplicity is why a lot of women like using them and these kits can make discovering when you're ovulating far easier.

Reasons you might want to use an ovulation test

Believe it or not, having sex at the wrong time is thought to be the most common reason that couples struggle when trying to get pregnant [5]. One theory is that being on birth control gives women a false impression that a 28-day menstrual cycle is the norm [2].

In reality, a perfect 28-day cycle happens less than 20% of the time [7]. This makes it super easy to miss your fertility window — simply because you did the math wrong on your cycle length. Ovulation tests can help couples narrow down their fertile window and plan for pregnancy.

Ovulation tests and fertility treatments

Sometimes ovulation tests are recommended as part of fertility treatments. By checking on LH levels, your doctor can get a better understanding of your ovulation patterns and adjust any fertility medications to suit your natural cycle [3].

In some cases, using an OPK test even helps women seek fertility treatments sooner. By tracking their ovulation patterns, they become aware that they aren't ovulating — a good sign they should investigate further with their doctor [5].

How do they differ from pregnancy tests?

Most ovulation tests work the same way as a pregnancy test — you pee on a stick. They are both looking for a spike in hormone levels, but they are seeking entirely different things.

An ovulation test wants to know if there is a luteinising hormone (LH) surge in your system. Whereas, a pregnancy test is looking for a spike in human chorionic gonadotropin (hCG).

hCG is a pregnancy hormone made by the placenta which peaks during the first 12 weeks of pregnancy. After this, it drops back down. When used correctly, home pregnancy tests are 99% accurate. The most common mistake is to test too early. The ideal timing is 1-2 weeks after you miss a period [2]. 

When should I take an ovulation test?

We would love to tell you that there is a single, definitive day when you can start testing. But we live in the real world — where natural processes have their own timelines. The answer to when to take an ovulation test will be a little different for each person and it may take a few months of testing to find your groove. What we can do is give you some places to start.

The majority of women ovulate between days 12-17 of their menstrual cycle. Based on this, if you start testing from days 10-16 of your cycle, it's pretty likely you'll catch your LH surge [7]. In good news, most ovulation test kits come with 5-7 sticks — more than enough to test each day [3].

PS. The first day of your menstrual cycle is counted as the first day of your period. So, when you’re hunting for day 10 — remember to start counting from the first day of your monthly bleed.

Other signs of ovulation

There are also some physical signs of ovulation you can keep an eye on — these can tell you when your body has reached its fertile days. These include:

  • Vaginal discharge that is slick or slippery, like an egg white
  • Minor abdominal pain (usually on one side of the stomach)
  • PMS symptoms like bloating, tender breasts, or moodiness [4].

It can be helpful to use a mix of math (counting your menstrual cycle length) and self-awareness (looking for natural symptoms) to determine the timing of ovulation. With a bit of trial and error, we know you’ll become a pro at timing your ovulation test.

Can an ovulation test detect early pregnancy?

An ovulation test was not designed to detect pregnancy, so it should not be used to test for it. But, if you haven’t yet realised that you're pregnant, you might keep using an ovulation test and getting positive results. In this case, it’s possible for an ovulation test to detect early pregnancy.

Most of the time, when you get a positive result, you can stop testing and get down to the fun of making a baby. But there are some scenarios where you may want to keep testing.

For example, you might get a weak positive result on the first day you tested and wonder if you’ve really hit your LH surge. You might also be new to ovulation tests and try using them a few times to get the hang of it. In these cases, it’s possible to test positive a few days in a row.

It’s normal to get a positive ovulation test for up to 3 days (or 72 hours) since that’s how long LH levels are high in your system [6]. If you have positive ovulation results for more than 5 days, it’s worth digging deeper. First, you can check if you’re using the test correctly. Read the manufacturer’s instructions to make sure you’ve followed them to the letter.

Second, you might have a condition that is interfering with the ovulation test results. PCOS is a surprisingly common condition that results in irregular ovulation [4]. If you have this condition, or if you suspect you might, then your ovulation test could be showing a false positive, due to a false peak in LH [6].

This means even though it showed up on the stick — your body didn’t follow through by releasing an egg. To investigate this one further, we recommend a chat with your doctor.

Third — and this is a big one — you might, just maybe, have picked up on early pregnancy. As we said earlier, ovulation tests are not designed to detect pregnancy. But, that doesn’t mean they can’t find it.

LH and hCG are the 2 hormones that peak during ovulation and pregnancy. They have incredibly similar chemical structures, which means the testing kits can be confused by which one it has detected.

While an at-home ovulation test is made to pick up on LH levels, it’s not sensitive enough to tell the difference between LH and hCG [6]. Long story short — if your ovulation test keeps coming up positive, it may no longer be detecting LH. It may be detecting HCG. The only way to know for sure is to move on with the appropriate test option: a pregnancy test.

How to use an ovulation test

Last, but never least — we wanted to share how to use an ovulation test. Hopefully, this helps you feel more comfortable with the process. We promise it’s really easy.

Like a pregnancy test, at-home ovulation tests are done with urine. Some of them use sticks while others use strips. Some of them ask you to pee directly onto the stick, while others want you to put it in a cup. Either way, taking an ovulation test is simple. You need to expose the test stick or strip to your urine so that it can show you a positive or negative result [3].

A lot of ovulation tests use 2 lines to show your results. Here’s what the lines mean [7]:

  • 1 line: This is the control line. It exists to show you the ovulation test is working. If you only see this line, then you have a negative result.
  • A second faint line: 2 lines means the test has worked, but it looks like there is no LH surge yet. You want your second line to be as dark or darker than the control line for a positive ovulation test.
  • 2 strong lines: Woohoo! 2 strong lines on an ovulation test means a positive result — you should be in your ovulation period.
  • No lines: Sorry, but your test did not work. Since the control line is not visible, it’s a sign that your testing kit may be faulty. Try again with another stick or buy a new ovulation test kit.

To get the best result from an ovulation test, most experts say you should use it first thing in the morning. This is because morning urine is more concentrated, meaning your LH levels will be nice and easy to detect [7].

Some women find it useful to write down the colour of their urine on different testing days. It can help you understand if hydration is affecting your ovulation test results.

It takes 2 to get pregnant, which is why we want to provide you and your partner with a preparation kit that has everything you need to start your conceiving journey.

Photo credit: Getty Images

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