I've been teaching the Boston Cross Check Method of Natural Family Planning (NFP) for well over a decade. One of the things I love about this method is that it doesn't fit neatly into a strict "category" because it offers so many flexible charting options. 

For those who are familiar with different types of charting methods, BCC is what we might call a sympto-thermal-hormonal method, meaning that it treats THREE key biomarkers for ovulation equally in our instruction.  All clients who learn the standard Method Instructional Program (MIP) with BCC will learn: 

• Cervical fluid ("sympto")
• Basal body temperature ("thermal")— this can be done with traditional oral temping or with Tempdrop*
• Hormone monitoring with the Clearblue fertility monitor ("hormonal")

Clients are encouraged to use all three indicators, but may pick and choose any combination of TWO biomarkers from this list to officially complete a "Cross Check" calculation to identify the end of fertility. Biomarkers will also be used in conjunction with historical cycle data to determine the start of fertility for each cycle. 

In addition to these three standard biomarkers, BCC instructors are also trained on how to incorporate optional hormonal testing: 

• LH testing
• PdG (progesterone) testing with the Proov system

These indicators do not substitute for any of the three primary biomarkers, but can be useful for additional information to increase confidence interpreting ovulation with a chart. For example: 

1. A client who is working with fluid + BBT for their primary two biomarkers may want to add in a hormonal component by tracking with LH tests. This saves money compared to working with the monitor, while adding another component to the chart which can help identify ovulation. Positive readings with an LH test, however, cannot substitute directly for PEAK readings on the Clearblue monitor either for identifying a Cross Check calculation, or for applying the cycle data algorithm to the start of fertility calculation. 
2. A client who isn't able to get reliable temps may want to include PdG testing in addition to the primary two indicators of cervical fluid + Clearblue monitor. This can help increase confidence knowing that any fluid and/or monitor PEAK readings led to successful ovulation. However, PdG testing cannot substitute directly for a confirmed BBT temperature shift either for identifying a Cross Check calculation, or for applying the cycle data algorithm to the start of fertility calculation. 

Beyond that, we also offer instruction for situations when you really only have on biomarker to work with in a particular chart. These are not ideal situations and the method isn't intended for long-term use this way, but if you're stuck on a chart and only have temperature data, we'll work with you!

So just to give you an idea of how flexible this method is built to be, here are the approved long-term combinations of markers that all BCC instructors are TRAINED to work with, within the official parameters of the method: 

• Cervical fluid + BBT + Clearblue
• Cervical fluid + BBT
• Cervical fluid + Clearblue
• BBT + Clearblue
• Cervical fluid + BBT (+ LH)
• Cervical fluid + BBT (+ PdG)
• Cervical fluid + BBT + Clearblue (+ LH + PdG)
• BBT + Clearblue (+ LH)
• BBT + Clearblue (+ PdG)
• BBT + Clearblue (+ LH + PdG)
• Cervical fluid + Clearblue (+ LH)
• Cervical fluid + Clearblue (+ PdG)
• Cervical fluid + Clearblue (+ LH + PdG)

Note: Anywhere you see "BBT" listed, you can substitute either oral or Tempdrop tracking

Note that some of these combinations actually double-cover certain data points. For example, if you are regularly getting a PEAK reading on your monitor, there's no need to add LH testing because you'd be looking for the same LH surge that the monitor is already picking up for you. So it's extra work for a data point that doesn't really get you helpful (i.e., actionable) information on your chart. But you're welcome to do it. 

This is why it's important to know the difference between collecting all the data, versus collecting meaningful data. It's not always the case that more data will equal a better charting experience or better clarity with your cycle. Sometimes that's true, but not always. 

Can it be even MORE flexible?

Here's where we get to the question a LOT of current clients or potential clients still like to ask, though. "Within the parameters of the method, can it be even more flexible?" Usually they are asking because they've heard about a new femtech device or tracking system that promises more data!

(But we're going to remember the important difference between more data and meaningful data, right?)

The two big areas where we see innovations in femtech right now are: 

1. BBT tracking with different wearable devices
2. Hormone monitoring with quantitative systems (e.g., a monitor that gives numerical results instead of just low, high, peak assessments)

So the questions I am typically answering are:

Can I substitute a new device for one of the other primary indicators? That is: Could I replace my Clearblue monitor with Mira or Inito? Or could I replace my Tempdrop with an Oura ring?

The short answer is: NO.

Here's a longer answer:

Your NFP instructor is never going to tell you that you can't purchase and use a particular femtech device. You're welcome to spend your money and time however you choose! But your NFP instructor is definitely required to tell you whether a particular femtech device is going to give you meaningful data within the official context of the method. 

For example— if you want to track the phases of the moon with your cycle, that's fine! Whatever. Totally cool. But Boston Cross Check is not built on research which would allow us to meaningfully incorporate that data into your chart interpretation. It's an extra data point that means nothing in the context of the method. 

HOW THIS APPLIES TO TEMP DEVICES

So if you wanted to track your temperature with a device other than one of the approved options, that's fine! Whatever. Totally cool. But Boston Cross Check is not built on research which would allow us to meaningfully incorporate that data into your chart interpretation. Wearable thermometers that track skin temperature are NOT the same as traditional BBT tracking with oral or vaginal temps. You may recall that there are different ranges of "normal" temperatures based on where you are taking the measurement. 

• A normal rectal temperature is going to be close to 99.5°F. This is also typical for vaginal temperatures.
• A normal oral temperature is a degree lower, around mid- to low- 98°F.
• A normal under arm (axillary) temperature has a much wider range of normal, anywhere from about 95-98.6°F. 
• A normal skin temperature has an even bigger range of normal, anywhere from 92.3-98.4°F.

So: the farther you get from the core of the body, the more range you introduce to those normal measurements. 

Now, two things: 

1. Temperature shifts for ovulation are calculated based on relative temperature data points, not absolute. So in theory, you can look for similar shift patterns across different temperature locations and still apply the same calculation to determine whether ovulation has occurred. But this is actually still just a theory! It's also possible that temperature tracking on the skin (e.g., finger or wrist) would need to show a smaller standard shift to confirm ovulation, due to distance from the core. Or it's also possible that you'd need to see a longer sustained shift to confirm ovulation, due to the relative instability and fluctuations of skin temperature compared to oral. We haven't done that seminal research yet, so we just don't know! 
2. To be fair: Tempdrop also does not have seminal research like this to show that axillary readings can apply the same calculations. But because axillary temperatures are closer to core temperatures AND we have almost a decade of user and instructor experience with the device to confirm a close relationship between the Tempdrop algorithm and oral temping patterns, some methods (like BCC) are comfortable using this device as long as it's done in conjunction with at least one other primary indicator with the method.

HOW THIS APPLIES TO MONITORS

I hope you can see how this same reasoning applies, then, to other fertility monitors. Marquette has been researching Mira protocols and does offer "soft" protocols for that device: but as of writing, they haven't published seminal research showing efficacy with standard protocols. So even though it may be tempting to see numbers as data points for your hormones, we don't have research to show HOW those numbers can be applied to algorithms for the start of fertility, or HOW those numbers could be used to determine the end of the fertile window. And even if we had some seminal research on that front which was convincing, BCC does not yet have a system for incorporating that data in a meaningful way into our method. 

BUT WHAT IF I REALLY WANT TO USE A DIFFERENT DEVICE?

As I said above, your NFP instructor is never going to tell you that you can't spend your money and effort on a fancy new tracking device. But here's what we'll tell you: 

If you want to use a different temperature tracking device from the method-approved options, this is just going to be extra data for you. It doesn't count as "BBT" as a primary biomarker, so for BCC you'd need to chart with fluid + Clearblue in order to satisfy the criteria for having two primary biomarkers. You would use fluid + Clearblue for your start- and end-of-fertility calculations. A temperature shift with this other device could serve as a sort of mental confirmation of ovulation, but doesn't affect your method calculations at all. 

If you really really really want to use Mira, we'll direct you towards a certified Marquette instructor who can teach you about using that device! But at that point, you need to learn the Marquette Model of NFP and would not be using BCC.  Within the parameters of BCC, if you want to use a different hormone monitor from the method-approved options, this is just going to be extra data for you. It doesn't count as the "Clearblue monitor" as a primary biomarker, so for BCC you'd need to chart with fluid + BBT in order to satisfy the criteria for having two primary biomarkers. You would use fluid + BBT for your start- and end-of-fertility calculations. Any monitor assessments could serve as a sort of mental confirmation of ovulation, but doesn't affect your method calculations at all. 

Hope this helps! And happy charting!

(Curious about the difference between Marquette and BCC? We've got you covered here!)

*This is a referral link for Tempdrop. You get a discount and I get a referral bonus if you purchase through this link!