Trying to conceive (TTC) centers around one key event in a woman’s menstrual cycle each month: ovulation! Ovulation occurs when an egg releases from an ovary. The egg then moves into the fallopian tube and is available for fertilization. Since experts believe sperm can live inside the female reproductive tract for up to five days, timing intercourse in the few days before ovulation is thought to give you the best chance of conceiving in a given month. The goal is for sperm to be ready and waiting when the egg is released. But how on earth do you know when that will be?
In this post, we’re going to explore the ovulation predictor kit (OPK) method, which is an ovulation tracking method that can help give you a better idea of when you might be ovulating each month! If you are new to ovulation tracking, I would recommend also reading my blog post on the calendar method and cervical mucus method. Beginning with those basics will give you a great starting point before diving into the slightly more involved OPK method.
Why Is Tracking Ovulation Important?
If you are TTC, identifying your fertile window (the few days each month you are most fertile) is key because it can be very easy to miss it. According to experts, the fertile window is comprised of the five days prior to ovulation and the day of ovulation itself. With such a small window to aim for each month, it is very helpful to gather as much information as possible that could provide hints of when you may be ovulating. You can then adjust the timing of intercourse to align with your fertile window. Doing so will help optimize your chances of becoming pregnant!
Things to Keep in Mind
Before we get started, I want to point out that I am not a doctor. My advice is based on extensive research as well as my own personal experience. It’s also important to note that these ovulation tracking methods are clues to help you estimate when ovulation might occur but are not a surefire way to pinpoint the exact timing of ovulation.
According to experts, the exact timing of ovulation can only be confirmed via ultrasound. But, yikes… that would get expensive! The OPK method is a lower-cost option and can be done from the comfort of your own home while still helping you gain some helpful insight into the possible timing of ovulation. With this in mind, let’s explore the OPK method and track that egg!
Ovulation Predictor Kits (OPK's)
This name sounds so magical, doesn’t it? A crystal ball would be super helpful right about now! OPK’s are an incredibly helpful tool that can help you better estimate when ovulation will occur. And unlike some of the other ovulation tracking methods, OPK’s give you a chance of having some advanced notice that ovulation is coming. And they do so via clear test results! I have personally used the OPK method, and my goodness… It has done wonders for helping me better understand my body, fertile window, and potential ovulation timing.
OPK’s are a urine test that are designed to detect a short-lived surge of Luteinizing Hormone (LH). Detecting the LH surge is helpful because the surge is thought to occur about 1-2 days prior to ovulation each month. According to experts, this surge of LH occurs once a developing follicle reaches a certain level of maturity. The LH surge then sends a signal to that follicle that it is time to release the egg.
So, if you are able to detect your LH surge via an OPK, it is thought that you can assume you will ovulate in the next 1-2 days. This is great news as you can make sure to have intercourse during this time in order to increase your chances of getting pregnant!
Intercourse Timing Tips
You should not wait until after you detect your LH surge to start having intercourse as you could be missing out on some of your fertile days. (Experts believe your fertile window begins about five days prior to ovulation, and the typical OPK gives you 1-2 days’ notice.) So, I would recommend having intercourse throughout the full estimated fertile window and using an OPK to help you capitalize on those last 1-2 days. Using an OPK can also help you with estimating your ovulation date and fertile window for future months (if it comes to that)!
I want to start by pointing out that each brand of OPK will have unique instructions on how to use it, so you should always follow those instructions to maximize the accuracy of your results. For purposes of this post, I will discuss some general guidance for using OPK’s.
OPK’s generally come in a pack of several tests. This is because the timing of the LH surge is not an exact science. You will typically want to start taking your OPK a few days prior to when you think you might be ovulating to increase your chances of “catching” the surge. (If you’re not sure when that is, no worries! The instructions for your OPK will help you calculate what day to start taking the tests based on your typical cycle length.) This means you will likely get a few negative results at first, and that is totally fine! It’s much better to take a few extra tests than to accidentally miss your surge.
If you’re not sure what your typical cycle length is and/or want to learn some basics on how to identify your estimated ovulation day, check out my post on the calendar method and cervical mucus method!
How to Use OPK's
You will typically want to start out by taking one test per day at around the same time each day. Unlike pregnancy tests which are typically taken first thing in the morning, experts believe OPK’s give the most accurate results when taken in the early afternoon timeframe. This is because many LH surges occur in the early morning hours, and it can take a few hours for the surge to show up in your urine.
It is also typically recommended that you limit water intake and hold your urine for at least four hours prior to taking the test. The test is more likely to detect an LH surge when your urine is more concentrated. You will usually be given the option to urinate directly onto the urine test strip or to urinate into a cup and dip the urine test strip in the urine. (I personally prefer the latter. If you do also, I recommend stocking up on these Dixie cups.)
The results of most traditional OPK’s are read by comparing the darkness of two lines, the control line and the test line. The “control line” is a standard darkness for all tests and is usually located the farthest away from the urine test strip. This is the line you will be comparing against. The “test line” is developed based on the level of LH in your urine and is usually located closest to the urine test strip.
If the test line is as dark as (or darker) than the control line, your results are considered positive. This means you can expect to ovulate within the next 12-48 hours. If the test line is lighter than the control line, your results are considered negative, and you should test again tomorrow. If there is no control line, the test is considered faulty, and a different test should be taken.
See below for an example of what your test results may look like and how to interpret them. In this instance, the LH test was positive and at its peak darkness on cycle day 12. This means ovulation can be estimated for cycle day 13 or cycle day 14.
Result Interpretation Tips
If you are having trouble getting a positive result, there are two things I would recommend doing. First, make sure you are testing on the right days of your cycle based on your estimated ovulation date. See my post on the calendar method and cervical mucus method for more information on how to calculate this! Second, consider taking two tests per day instead of one. If your LH surge is very short-lived, it is possible for it to come and go within 24 hours. This might cause you to completely miss it if you’re only testing once per day.
If comparing the line darkness is stressing you out, you may prefer a digital option to remove the subjectivity. Digital OPK’s provide very easy-to-read results, and I discuss some of my favorites in the My OPK Favorites section.
Combining Ovulation Tracking Methods
If you use the calendar method and cervical mucus method, you will likely already have a general idea of when you might be ovulating. Once you identify the few days when you think you are expecting ovulation, you can start taking your OPK tests a few days before that time. Make sure to also use the instructions in your OPK as a reference for when to begin testing.
The OPK method is even more powerful when combined with the basal body temperature (BBT) method because the two methods together create an “ovulation sandwich.” (Check out my post on the BBT method for details on how to incorporate it into your ovulation tracking activities.) Since the OPK method gives you about 1-2 days’ notice prior to ovulation, and the BBT method estimates ovulation 1-3 days after it has occurred, the estimated ovulation date is thought to be sandwiched between the two.
For example, in the visual shown above, the OPK test turned positive on cycle day 12, which led us to believe ovulation would occur on cycle day 13 or 14. If the BBT method was also being used and the temperature shift occurred on cycle day 14, you could then reasonably estimate that ovulation occurred right in the middle on cycle day 13. So cool! That is why using both the OPK and BBT methods allows you to estimate ovulation with more precision. The more tools you incorporate, the more insights you will gain.
My OPK Favorites
- Clearblue Advanced Digital: This is one of the most popular OPK’s out there. What’s great about it is, unlike many alternatives, it tests for two key fertility hormones (LH and Estrogen). It is advertised as typically identifying four or more fertile days (at least 2 more days than any other test). It also gives you your results in the form of a smiley face, so there is no room for confusion. (No more squinting at a line test trying to figure out if it’s positive or not!) If you’re looking for an easy-to-read OPK that gives you more of a heads up on ovulation than the 12-48 hours we discussed above, I would definitely recommend looking into getting the Clearblue Advanced Digital Ovulation Test.
- Pearl Fertility: I was recently gifted the Pearl Fertility Hormone Tracking Kit and had the opportunity to try it out. It is way more than your average OPK! It comes with 15 FSH tests, 15 LH tests, 2 hCG (pregnancy) tests, a reusable test strip holder, and access to the Pearl Fertility app to visually track your hormone patterns and peak fertility days. (Similar to Clearblue Advanced Digital, your results are interpreted for you, so you won’t have to squint at any lines.) Adding FSH tracking to my typical LH tracking actually helped give me advanced notice that my LH surge was coming, which was awesome!
- Easy@Home: The only downside with the two options listed above is that they are a bit more expensive than some alternatives. If you are looking for a less expensive option and are okay with getting the typical 12-48 hour heads up on ovulation, I would definitely recommend looking into Easy@Home Ovulation Test Strips. They are cheaper, have great reviews, are supported by an app, and even come with some pregnancy tests to use a couple weeks later!
When you are TTC, you naturally want to do everything you can to optimize your chances of becoming pregnant. One of the most helpful things you can do is align intercourse with your fertile window. If you have intercourse during the days leading up to ovulation and/or on the day of ovulation itself, you increase your chances of sperm being able to meet up with the egg and fertilize it.
Being able to optimize the timing of intercourse directly depends on estimating the potential timing of ovulation with as much accuracy as possible. By incorporating the OPK method, you can begin to gain some great insights into when your egg might be released each month.
I would love to hear about your experiences with ovulation tracking! If you have any questions or additional insights pertaining to the OPK method, please share them via the comment box below.
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