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A handful of times, I've encountered a parish priest or marriage prep coordinator and, after mentioning the Marquette Method of NFP, they say “Oh, that thing with the thermometer! Yeah, we have someone who teaches that.”
Time for a lesson, folks.
When we’re talking about the Marquette Method, it’s most accurate to call it a highly-effective, well-researched, and modern method of identifying the shared fertility of husband and wife for the purposes of planning when to have a baby.
I guess that’s kind of a mouthful, eh?
Really, you could say the Marquette Method is “the thing with the monitor, or cervical mucus, or the thermometer, or that other monitor, or that other urine hormone test…” so thinking about which tools are at our disposal to identify fertility can be a really helpful way to think about what NFP is. We won’t forget that NFP requires integration of the whole human person and authentic self-giving love between husband and wife as we endeavor to focus on some technical aspects of NFP below!
Here’s a link to our overview of the basics of the Marquette Method, but in this post, we’ll go into detail on just one of our “bonus” charting tools: OPKs.
What we'll talk about:
What are OPKs?
OPK stands for “Ovulation Predictor Kit,” and they are a qualitative urine hormone test that detects the presence of luteinizing hormone (LH). They are also commonly referred to as LH tests, and your instructor might use the terms OPK and LH test interchangeably.
We already used some big terms here!
Qualitative means the test will give us a “yes or no” or quality result, in contrast with a quantitative test that will give us a numerical value or quantity result (the Mira monitor provides quantitative data). OPKs will tell you a “yes or no” result about whether or not LH is at high enough values to stimulate ovulation.
LH is the hormone that rises really high, really quickly, just before ovulation. This surge in LH signals the ovary to release the egg, so by detecting the LH surge, we can predict when ovulation is about to occur, relative to other signs and symptoms of fertility. LH is always at some detectable level, so if you test with an OPK every day, you’ll likely see at least a faint line indicating that LH is present. It’s when you see a nice DARK line that LH is rising high enough to cause ovulation (again, given the context of the whole cycle!).
What do they tell you about fertility (and what do they NOT tell you)?
LH tests identify a short window of fertility (only 24-48 hours before ovulation), whereas the entire fertile window (when you can actually conceive) is about 6 days. This means OPKs are best used in conjunction with mucus and/or the monitor for determining the entire fertile window for avoiding pregnancy. They may help you identify "peak" days of fertility, but not "high" days.
Since they’re just telling you about one hormone that only stays high for a day or two, it’s really essential that you’re looking at more data than just LH to determine when you’re fertile and when you’re not. These tests also don’t confirm ovulation, they just predict that ovulation is likely about to occur. (Ask your instructor for ways to confirm ovulation. Hint: it’s a different hormone we’d be looking for!)
When would they be helpful?
There are three times I recommend my clients use OPKs: postpartum, perimenopause, and PCOS. I’m sure some of you can see what these have in common…
...the letter P!
…and they are also all times when hormones are doing WACKADOODLE things.
The Clearblue monitor, our mainstay with the Marquette Method for many years, gives qualitative data on two hormones, estrogen and LH. When the Clearblue monitor gives you a “peak” reading, it’s detecting the LH surge. In practice, if you tested with an OPK using the same urine sample that the monitor uses to record a “peak,” you should see a positive OPK result as well. Knowing this information is very helpful for these three times I mentioned above!
Postpartum: The first few cycles postpartum can be very long, and sometimes this means the monitor will reach a point that you can’t keep testing, and you have to use our tricks of the trade to know what’s going on with your cycle. When this happens, there’s a higher chance you can miss a day of testing, and not detect the LH surge with the monitor. However, since you can test with OPKs any day at any time, you can supplement with these tests even if you can’t test with the monitor, and still know when your LH surge is! This is a time that following up with your instructor is essential, as things can get confusing pretty quickly.
Perimenopause: When hormones start to change in the 10-15 years before menopause, LH isn’t excluded from these weird ebbs and flows. LH levels can start to be relatively higher or lower than a woman in her prime reproductive years, which means the Clearblue monitor may be less likely to detect a “peak” reading. If a woman is using the monitor and not detecting peak as expected, my first recommendation is to add a daily test for LH using the OPKs.
PCOS: With PCOS, or Polycystic Ovary Syndrome, LH levels can sometimes run higher than normal, and some clients can use OPKs to know if they fall into this “type” of PCOS. I usually recommend these clients confirm ovulation with temperature or progesterone testing as well, since the predictive value of LH won’t be as helpful if LH always looks like it’s at ovulatory levels. PCOS is a time where you absolutely need to follow up regularly with your instructor!
I’ve also found OPKs are handy when traveling. The monitor isn’t terrible for travel, but when traveling across time zones, or trying to go camping in the wilderness, it can be a little cumbersome. The OPKs are a little more mobile, disposable, and don’t require a strict testing schedule like the monitor does. I personally can attest to the helpfulness of OPKs from our recent two-week family road trip, where I used OPKs and mucus to determine peak without issue!
How much do OPKs cost?
CHEAP!
I love that OPKs are the cheapest hormone test out there. They have their drawbacks, considering you need to chart other signs to ensure you have an accurate picture of your fertility, but I recently bought a box of 50 tests for $10 USD. Not a bad deal.
You can find a link to one brand of OPKs, as well as other tests and tools, here.
Pros and cons of OPKs
Pros:
Cheap
You can test with them any day, any time
Can help at times when the monitor may be more tricky
Help to “double check” other signs and symptoms of fertility
Easy to travel with
Cons:
Comparison of OPKs with other charting tools
Charting biomarker | OPK | Clearblue Monitor | Cervical Mucus | Temperature | Mira Monitor |
Hormones | LH | Estrogen, LH | Estrogen, Progesterone | Progesterone | Estrogen, LH, Progesterone |
Days per cycle observed | ~10-15 | ~10-15 | Daily | Daily | ~10-15 |
Cost (as of July 2024) | $0.30 /test | $1.80/test One time cost of monitor: $120 | $0 | One time cost of thermometer: $15 Wearable thermometer (optional): $220 | $3.25-$4.45 /test One time cost of monitor: $200 |
Predicts ovulation | Yes | Yes | Yes | No | Yes* |
Confirms ovulation | No | No | No | Yes | Yes* |
* E3G and LH test wands predict ovulation, PDG wands may confirm ovulation but more studies are needed.
Summary
Of course, all of this information will be the biggest help to you if you chat it over with your instructor! If you don’t have an instructor yet, we’re glad to get you connected ASAP. You can find an intro class, or schedule a consultation if you’ve already learned the Marquette Method before, with one of our fantastic Marquette Method instructors at Whole Mission!
Direito, A., Bailly, S., Mariani, A., & Ecochard, R. (2013). Relationships between the luteinizing hormone surge and other characteristics of the menstrual cycle in normally ovulating women. Fertility and Sterility ,99(1), 279–285. https://doi.org/10.1016/j.fertnstert.2012.08.047.
Barron, M.L., Vanderkolk ,K., & Raviele, K. (2018). Finding the Fertile Phase: Low-Cost Luteinizing Hormone Sticks Versus Electronic Fertility Monitor. MCN: The American Journal of Maternal/Child Nursing , 43 (3),153-157. DOI: 10.1097/NMC.0000000000000422. PMID: 29489529.
Mu, Q., Fehring, R. J., & Bouchard, T. (2022). Multisite Effectiveness Study of the Marquette Method of Natural Family Planning Program. The Linacre quarterly, 89(1), 64–72. https://doi.org/10.1177/0024363920957515
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