Using OPKs to Pinpoint Ovulation

Whether you're trying to conceive or you want to track your cycle to better understand your body, OPKs (Ovulation Predictor Kits) are commonly used to determine when you ovulate based on hormones released by your body. They are one of my favorite ways of determining ovulation because they are fairly easy to use and pretty damn accurate, but of course they do come with a few perimeters and a bit of a learning curve.

Which ones to buy? When to test and how? And what do these tiny pee strips actually mean? I'm going to explain it all for you right now.


Why to use them

If you're new to cycle charting or trying to conceive then you may be asking why you even need OPKs at all. Especially if your doctor told you something to the tune of, "oh just have sex on cycle day 10, 12, 14, and 16" or if you're using a cycle tracking app that shows you which days you're most fertile, then that's all you need, right?

Well, not necessarily. Yes these are methods for estimating ovulation, and if you have a 28 day cycle they may even be correct for you, or really close to it, but at the end of the day it's still an estimation. If you want to know for sure when you're ovulating, then you've got to look at some of the signs your body is giving you.

I find OPKs to be one of the easiest and most accurate methods because they are actually quantifying what's happening with your hormonal ebbs and flows. There's also Basal Body Temperature (BBT) charting, as well as observing cervical fluid and position, but I have most my patients start with OPKs.


Which ones to use


Many of my patients like to use fertility monitors, such as ClearBlue, to track ovulation. These are a bit more high tech because they involve plugging the tests into a small machine that signals low, medium, or high fertility because they track both luteinizing hormone and estrogen levels.

The thing is, some women's hormones aren't exactly synched up the way the monitor is programed to look for, so they never get the high fertility signal and are left confused about when ovulation is actually happening. And, of course there's also always the possibility of the monitor acting glitchy or not working at all.

If a fertility monitor works for you, great! If not, I much prefer the analog ovulation strips (like these) that simply have one line for negative and two lines for positive, because they only track the rise in luteinizing hormone. This way, when you use these OPKs every day you can see the line get darker and darker until it peaks, simple.

These tests are also usually a bit cheaper, especially the dip strip format, so you can buy a ton in bulk. The only downside there is you have to pee into a clean cup first before dipping the test strip in - depending on where you are when you test, this might require some coordination, or you might opt for the slightly more expensive midstream version (like these).


How and when to use them 

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OPKs are designed to test your urine for luteinizing hormone, which peaks mid-day, so I usually recommend testing sometime between noon-5pm.

Some instructions say to test the first pee of the day, but I'm not really sure why because it may give you a low reading. I've seen some women use OPKs throughout the day on their peak day and you can see the dark line arrive in the afternoon.

If you estimate that you ovulate on cycle day 14, then start testing on cycle day 9 or 10. If you estimate a different day for ovulation, then plan to start testing 4-5 days prior to when it's estimated you ovulate, and test every day until after you get a positive.

Some tests also often recommend you stop testing once you get a peak, but some women get at least 2 or 3 days of luteinizing hormone peaking before ovulation actually occurs. You can't know which day was your peak day unless you see another negative test again.


How to track them

If you're going through the trouble of taking these tests I think it's important to track the information somewhere so you can see what your patterns are and predict when ovulation will happen next cycle.

You should also keep track of the first day of your period each cycle, this is known as cycle day 1 and each sequential day is counted until you get to the next cycle. Ovulation is estimated as cycle day 14, or approximately 14 days before the next estimated period, but it can vary widely from woman to woman.

I recommend using a cycle tracking app, such as KindaraFertility Friend, or Glow. They all allow you to mark which days you get positive OPKs. If you are using a fertility monitor, then only mark the days you get a high fertility signal as your positive OPKs.

If you are using the analog OPK strips, I also recommend either labeling each one with the date and storing them in a small ziplock bag, or take pictures of them and save them in an album on your phone. This way, when you're trying to figure out if the line is darker today than it was yesterday, you can compare the two and see for yourself.


Having trouble spotting ovulation? 



It can be somewhat common that even with precise use of OPKs there's some confusion as to when and if ovulation is happening. If this is the case for you consider using Basal Body Temperature (BBT) charting to get a better idea of what your hormones are doing.

If you are ovulating then you'll see a surge in temperature at ovulation when your body shifts into the next phase of the cycle and starts making progesterone. You can also use urine test strips to test for progesterone after you suspect ovulation to see if it happened.

If you try these methods and still don't see signs of ovulation, it is possible that you're not ovulating, which is an issue if you're also trying to conceive. Some intervention may be needed to get ovulation going again. I treat anovulation (lack of ovulation) often with a combination of acupuncture, herbal medicine, and diet, which often work quite well at jump starting the ovaries. However, it's not an instant process, it can take a few months to get the body balanced.

If you suspect you're not ovulating, or if you're having a lot of trouble figuring out if you are, make sure to work with a healthcare provider to create a plan that makes sense for you. If you'd like to work together to regulate your cycle you can learn more about acupuncture, send me a message, or make an appointment.


Want to learn more?


I discuss using OPKs, along with a ton of other topics in Foundations of Fertility - my 6-week masterclass in all things fertility. In fact, we cover hormones and common hormonal imbalances, diet, supplements, herbs, Chinese medicine, cycle charting, and how to evaluate your own fertility. If you're serious about trying to conceive this course is for you!