Your Top Questions About BBT Charting Answered (Episode 531)

Full Transcript: Episode 531

Lisa: Today I thought I would do a follow-up to last week’s episode. In last week’s episode, we went through a research paper that went through the differences between oral temperature taking and using wearable devices. And in today’s episode, I’m going through your top questions about BBT charting. So without further ado, let’s go ahead and jump right in.

All right, BBT. BBT is an interesting topic in the fertility awareness world because I think the majority of women are familiar with the symptothermal method. I would say the majority of my clients and the majority of practitioners tend toward the symptothermal method, which is a combination of cervical mucus charting, BBT, and other signs including cervical position and other secondary signs. However, it is important to recognize that there are methods that are used without the BBT. And there are actually practitioners who discourage the use of BBT. So it can be helpful to understand why.

One of the reasons that some practitioners and some methods avoid the use of BBT is because BBT is variable. It changes and fluctuates based on a variety of different factors that are happening in your life. Now I would argue that that is one of the reasons that makes BBT a really helpful measure, especially when you’re looking at the menstrual cycle as a vital sign. And for my FAMM practitioners, BBT analysis is one of the most important aspects of the chart — because it does give us an additional measure of metabolism so that you can guide your client in terms of how much they’re eating to ensure that they’re getting enough overall food and protein and overall calories to support their activity level and hormonal balance. It can be used to identify potential underlying issues like thyroid disorders. And it can tell us about what’s happening in your life — whether you’re getting enough sleep, how stress is affecting you, or even how allergies and different things that could trigger the immune system affect your temperature.

From the charting perspective, the temperature is really helpful to confirm ovulation. So there are a lot of really great applications for it. I certainly am in favor of using it. But it is helpful to know that there are methods that do not use it. It’s also helpful to know that with mucus-only methods — methods that use mucus without temperature — you can actually accurately confirm ovulation without temperature, although I prefer to have the secondary sign of basal body temperature as a way to correlate and cross-check. There are plenty of women out there using mucus-only methods who are equally confident in confirming their ovulation without it.

So let’s go ahead and jump into the common questions I receive about BBT.

The question I get most frequently is: what kind of thermometer do you use, or what kind of thermometer should I use? My advice always goes like this: in order to get an accurate temperature when you’re charting, you don’t need a fancy expensive thermometer. You can accurately chart your temperature with a $5 to $20 thermometer. The most basic requirement is that the thermometer measures to at least one decimal point — most thermometers these days measure to two decimal points, so you’re going to be fine. There are features that can be helpful: a thermometer that remembers your temperature, a backlight, the ability to switch between Celsius and Fahrenheit. And then of course there are a number of wearable devices including the TempDrop that allow you to wear the device throughout the night, it spits out a temperature for you, and it syncs to your devices so you don’t have to remember to input it manually.

Second question: what is a normal pre-ovulatory temperature? The reason I specify pre-ovulatory is because you will have a different set of temperatures before and after ovulation. Generally speaking, before ovulation — and ignoring the period temperatures which often fluctuate as your hormones adjust — all of those pre-ovulatory temperatures should ideally be higher than about 97.4°F or 36.3°C approximately.

Where does that number come from? Well, we’re all human beings and there is a normal ideal average temperature. I hear this a lot: “I’ve been doing my temps for a while and I just figured my temps are just lower.” When we’re looking at the menstrual cycle as a vital sign, if your temperatures are too low, that is telling you something. One of the pieces of feedback I often get about my fertility awareness mastery charting workbook is that in the Fahrenheit book, 97.0°F is the lowest temperature — if your temperature falls below that you have to write it off the chart. Similarly, in the Celsius book, 36.0°C is the cutoff. I often get: “Well, where’s the temperature chart for those of us who have low temperatures?” And I respond by saying: the reason the chart ends there is to notify you that there’s a problem. Whether it’s that you’re not taking your temperature correctly, or whether there’s something going on nutritionally, with thyroid function, with sleep — that cutoff is there to serve as a final word that if your temperature is off the chart, we’ve got to look at what’s wrong and fix it.

Obviously, my recommendation for correct temperature-taking is to hold the thermometer in place for 10 minutes before you push the button. That allows the thermometer to warm up and the temperature to stabilize. For some women, just by doing the 10-minute rule, they get that BBT up to a normal range. When you’re using a digital thermometer it gives you a reading within 10 seconds or 20 seconds — and that’s often not long enough.

What’s the normal post-ovulatory temperature? It needs to be in a higher range than the pre-ovulatory. That could be 97.8°F and higher, with at least a few temperatures hitting over the 98.0°F mark. In Celsius, we’d expect some of those post-ovulatory temperatures to be over 36.6°C or 36.7°C, sometimes hitting 37.0°C or close to it.

Third question: does my BBT help me to predict ovulation? The short answer is no. Basically, the change that we’re measuring in the temperature is a result of a hormonal shift that happens after ovulation. Before ovulation, we’re making a lot of estrogen as our follicles develop. Once you ovulate, that is what triggers the production of progesterone — and progesterone raises your body temperature. It has a thermogenic effect on the body as it’s preparing you for pregnancy. So we ovulate first, and then we have the progesterone rise second. And that progesterone rise is what raises our body temperature. If you haven’t ovulated, you’re not going to see what’s called a sustained BBT shift. Basically, if you’re charting your temperatures, you’ll have temperatures in a certain range in the pre-ovulatory phase, and then after you ovulate, you’ll see a rise and it’ll stay high.

The rise on the day after ovulation isn’t always exciting — sometimes it’s just rising one point or half a point higher than the highest of the previous. But what we’re looking for is that shift. If you look at the chart several days after ovulation, you would expect to see two distinct groups of temperatures — one group lower and one group higher — and you should be able to draw a line through the graph. So the answer is: BBT does not help you predict ovulation, it helps you to confirm ovulation.

Fourth question: how do I tell that I’ve ovulated? At the most basic level we’re looking for three temperatures that are higher than the previous six — three temperatures that are normal, not disturbed. Not because you had a fever, not because you drank alcohol the night before. Just higher than before. And what we’re looking for is that shift. If you’re also charting cervical mucus, you would be charting the lotion-y or white type mucus, the clear stretchy type mucus, and once you ovulate, the progesterone rise will also shut down mucus production. There’s a distinct shift in terms of the quantity and quality, and in a normal typical cycle the mucus should dry up after you’ve ovulated.

Fifth question: what do I do if my temperatures are erratic? The first thing to do is consider holding the thermometer in place for 10 minutes. You have the thermometer off, place it in your mouth for 10 minutes so it warms up, then once those 10 minutes has passed, you turn it on and take your temperature. A lot of my clients will hit the snooze button and use that 10 minutes to do this. For the majority of women I work with, this actually helps stabilize temperatures without any other changes needed. Another option is to consider a wearable device, since the warming-up issue is not really there and that can often help stabilize erratic temperatures.

If you’ve been taking your temperature correctly and are still seeing lots of ups and downs, there are other factors to look at. How many hours are you sleeping? If you’re sometimes getting 5 hours versus 6 or 7, that can make a difference. Getting up at different times can make a difference — if you usually get up at 6 and on weekends you sleep until 8 or 10, that can affect things. Some women are sensitive to alcohol the night before. Seasonal allergies can cause temperature shifts. There are a lot of different factors.

What I recommend is to start actually tracking on your app or paper chart what factors affect your temperature. Record the time you take your temperature each morning. You can create a custom line for how many hours you slept, or for known factors like alcohol consumption, allergies, or illness. Use the comment section for disturbances like travel or time zone changes. When you’re sitting in front of your chart seeing a weird temperature pattern, often we want it to mean some crazy thing is going on — we want to think we’re the exception to the rule. But often there’s a much more basic and simple explanation.

Sixth: what if my temperature rises and then falls back? Again, refer back to the previous question — there are a lot of reasons why the temperature could go up. Sometimes you notice one temperature is super low and then the following day the temperature rises a little bit, but because the temperature before was so low it looks like a dramatic rise. Maybe you only had 4 hours of sleep, or you were disturbed that night. We have to consider all the other factors.

In terms of confirming ovulation, we always want to take it back to the rules. At the most basic level, we’re looking for three temperatures higher than the previous six. I also teach my clients and practitioners the advanced temperature rules so we can be a lot more clear and specific about how to confirm ovulation in tricky situations. Basically, for the purposes of this episode: if it doesn’t meet the rules — if you don’t have three temperatures that are higher than the previous six, if the temperature falls back down and continues to go up and down below the baseline — you probably haven’t ovulated. If the temperatures really are up and down and erratic, and multiple temperatures are dropping below that line, then you probably didn’t ovulate. The temperature is a reflection of what’s happening hormonally. If you’re not making progesterone, you’re not going to have temperatures that stay above that line.

Seventh: what if I don’t always wake up at the same time every day? I don’t think it’s necessary for you to force yourself to wake up at the same time every single day. What you need to do is record what’s going on so that when you get to the end of your chart you can look back and analyze it correctly. I recommend that you mark down what time you woke up and how many hours you slept, especially if it’s not always the same. If when you’re waking up later your temperatures are higher, you’ll start to see that pattern. Charting needs to fit into our lives — we shouldn’t be forcing ourselves to fit into the charting scenario.

For shift work specifically: the first step is to just do it. Take your temperature and mark everything down and see what happens. I think sometimes we get in our heads so much that we assume it’s going to be really bad. I’ve had clients who do shift work and it’s actually not even that bad — there are a couple of days that are kind of weird, but we can allow for that. Other times when your schedule is that erratic, it does make sense to consider using a wearable so you can have some stability there. Don’t just throw the baby out with the bathwater.

For postpartum: before your period has returned and before you start ovulating again, it does make sense to consider doing mucus only for a while. I do suggest you work with an instructor to make sure you’re good with mucus first. Temperature is less relevant for the purpose of confirming ovulation when you’re not ovulating. Once your period does start coming back, you can consider just taking the temperature when you can and using a wearable if it’s just too much with a baby.

Now, wearable thermometers and devices. I’ll just preface this by saying that beyond the TempDrop I haven’t tried every single device. There are a couple of general themes of wearables to be aware of. When it comes to classic charting and using the menstrual cycle as a vital sign, we’re using basal body temperature — which is a measure of your resting metabolism. To get that baseline metabolism, theoretically you need a minimum of five hours of uninterrupted sleep.

With a lot of wearable devices, what they’re doing is taking your temperature throughout the night and then spitting out an average temperature. So for many of these devices, it’s not actually a BBT you’re getting — you’re getting an average sleep temperature. The pros: that type of temperature taking, giving you that stable reading, really does in a lot of cases take out some of that irregularity of the temperature. I’ve seen many charts from wearable devices where having the device on your person, taking that temperature on a regular basis, stabilizes it so that when you’re looking for the temperature rise and looking to confirm ovulation, it allows it to be more stable and easier to confirm. Another pro: if you’re wearing it and it’s syncing to your device, it’s a lot easier — a lot of us love checking our phones and apps, and it just makes everything easier.

Some of the potential cons: because it’s taking an average sleep temperature, if I want additional information about the metabolism and that kind of information for the purpose of deeper chart interpretation and using the menstrual cycle as a diagnostic, I will often ask my clients and practitioners to also take their oral temperature. And I’ve had many clients who actually wear their device and do an oral temperature and do both on the chart. Not everybody does that — I don’t ask everybody to take two temperatures — but at the beginning of your charting journey, if you do have concerns about a variety of health-related things tied into your charts, that can be helpful.

There are certain devices worn as a ring on your hand, or on your wrist, or in other places. When you’re taking the temperature on your wrist or finger, that is actually not one of the three standard ways to get your BBT. The three common ways to get your BBT are orally, axillary, and vaginally. So if you’re doing it on your wrist, it stands to reason that the temperature might be a little bit lower. The benefit of these wearables is that they do help you to confirm ovulation — they’re helping you to see the difference between the pre-ovulatory temperatures and the post-ovulatory temperatures. So instead of the temperature range being the meaningful thing, you’re really looking for that shift and you’re looking to confirm ovulation.

Of course, I recommend if you’re using a wearable device that you also learn about your mucus so you can have a secondary sign to confirm, because it is important to do a cross-check — confirming that the mucus has dried up alongside the temperature shift to make sure that you have in fact ovulated. Learn a specific method, choose a method, follow it, learn the rules, and incorporate the wearable device into your existing knowledge of fertility awareness. Don’t just rely on the device by itself to be magical — because nothing’s magical. You need to be magical. The best application of tech to fertility awareness comes in an informed way.

And I’ve always thought the same way with all tech, whether it comes to charting apps or whatever that predict your ovulation. I don’t think an app can predict your ovulation. The point of fertility awareness charting is not to predict ovulation, it’s to confirm ovulation and to identify your fertile days. Identifying which days you’re fertile is not predicting ovulation — it’s knowing on that day that it’s a fertile day and then confirming ovulation with the signs.

The takeaway: wearable devices can be incorporated into your charting methodology. There are a lot of great pros for using them depending on your situation. For a lot of my clients, they really love having the flexibility of a device that syncs with their apps and they’re not having to remember to take their temperature. For other clients, they love their oral temping — especially for those wanting that additional diagnostic information about metabolism, thyroid, nutritional adequacy, and hormonal health. And like I said, I have a handful of clients who chart both.

So to recap: we covered BBT’s two distinct categories of application — confirming ovulation and the diagnostic implications. We covered why not all methods use BBT and why. What kind of thermometer to use. What’s a normal temperature range. Whether it will help you predict ovulation. How to confirm ovulation. What to do if your temperatures are erratic. What if temperatures rise and fall. What if you don’t wake up at the same time every day. Postpartum charting. And wearables.