How To Track Temperature for Birth Control and Fertility
TABLE OF CONTENTS:
What is basal body temperature?
What basal body temperature tells us about our fertility and hormonal health
How to check basal body temperature
Do you really have to wake up at the same time every day?
Adjusting late & early wake up temperatures
Things that can disrupt temperature recordings
What if I forget to take my temperature sometimes?
Can I use the Oura Ring, Apple Watch, Natural Cycles, etc?
What if I wake up a lot during the night?
What type of thermometer do you need to track BBT?
Here at Sauvage Wellness we use and teach the symptothermal double check method of fertility awareness which requires us to track cervical fluid and to track temperature for birth control and fertility.
WHAT IS BASAL BODY TEMPERATURE?
The temperature that we track for this method is called our basal body temperature (BBT). BBT is our temperature first thing in the morning before getting out of bed after at least 3 hours of uninterrupted rest. Waking temperature is known to be low in the pre-ovulatory phase and rise slightly during, or just after, ovulation and then remain high until our next period begins. This is what is referred to as a biphasic temperature pattern. By tracking waking temperature a woman is able to observe this rise in temperature which tells her she has ovulated AFTER it has happened.
These temperature shifts occur as a result of the changing levels of the hormone progesterone throughout the menstrual cycle. As progesterone rises following ovulation it causes a rise in basal body temperature. Near the end of the menstrual cycle progesterone begins to decline which causes a decrease in basal body temperature. Should a woman become pregnant, basal body temperature will remain high due to the high levels of progesterone maintained by the corpus luteum in the early phase of pregnancy.
It is important to note that temperature does not tell us the exact moment that ovulation has occurred. Rather it informs us that ovulation has occurred AFTER it has happened. It is also important to note that temperature does not tell us anything about IMPENDING ovulation, which is important because most pregnancies happen from unprotected sex BEFORE ovulation occurs. Cervical fluid is what tells us about impending ovulation.
If there is a chart in which no discernable temperature shift is seen, it may point to an anovulatory cycle where ovulation did not occur at all. This would inhibit a temperature rise because the progesterone needed to raise temperatures is produced only AFTER ovulation occurs.
WHAT BASAL BODY TEMPERATURE TELLS US ABOUT OUR FERTILITY AND HORMONAL HEALTH
While BBT tracking is so important for accurately confirming ovulation and closing our fertile windows, it’s also an important tool for better understanding our hormonal health and spotting potential imbalances that can lead to fertility struggles and period problems.
BBT tracking can help us…
Spot an underactive thyroid - lower than average BBT both before and after ovulation can be a sign of hypothyroidism
Uncover luteal phase defect - when there are less than 10 high temperatures following ovulation it can mean that the luteal phase is too short to support implantation which can lead hinder one’s ability to get pregnant
Spot an estrogen/progesterone imbalance in the post-ovulatory luteal phase of the cycle which is a leading cause of heavy, long periods
Know if we’re pregnant before even taking a pregnancy test - 18+ high temperatures after confirmed ovulation is an early sign of pregnancy
HOW TO CHECK BASAL BODY TEMPERATURE
To check our basal body temperature we must take our temperature first thing each morning before getting out of bed after three or more hours of rest using a fertility-focused thermometer. It is ideal that temperature is taken at the same time each morning because our basal body temperature rises as we shift further into the morning and mid-morning hours, which could skew accurate temperature readings.
Now if you’re freaking out thinking, “WHAT?! I can’t wake up at the same time every day? What if I want to sleep in on the weekend?” or “I’m never going to remember to take my temperature each morning.” or even “What if I wake up a lot and don’t really get three hours of sleep in a row every morning?” Do not fear, you can still accurately track your basal body temperature. Let’s troubleshoot these concerns.
DO YOU REALLY HAVE TO WAKE UP AT THE SAME TIME EVERY DAY?
“I can’t wake up at the same time every day? What if I want to sleep in sometimes?”
I get it. I am not a robot, and I do not wake up at the same time every day. Heck, other than my toddler’s cries of annoyance from his crib I don’t have an alarm clock. I sleep in when he lets me. When I was in my twenties and slept in until 10 am or later on the weekends, I still accurately tracked my BBT. None of my clients wake up at the same time every day. They sleep in on the weekends and vacations and still accurately track their BBTs too. So, how do we do it? We use the simple formula for adjusting late and early wake ups that is built into the symptothermal double check method and something I teach in much more depth in my Cycle Wisdom Course.
ADJUSTING LATE & EARLY WAKE UP TEMPERATURES
Temperatures will be higher if taken later than usual. 0.05 degree Celsius or 0.1 degrees Fahrenheit can be subtracted for every extra half hour slept. Temperatures will be lower if taken earlier than usual. Add 0.05C degree Celsius or 0.10F per half an hour between normal and actual wake up time. On the current Sauvage Wellness cycle tracking chart this equates to moving temperatures DOWN one box for every half hour that we over sleep and moving temps UP one box for every half hour that we wake up early.
THINGS THAT CAN DISRUPT TEMPERATURE RECORDINGS
Other things that can impact temperature include: drinking alcohol, travel, illness, stress, certain medications, and using a different thermometer. If temperature readings are wildly off because of any of these factors we cannot use those temperatures. We circle them and skip over them, considering them disturbed temperatures that are incapable of being adjusted for.
A word on alcohol impacting temperature…
I get asked about this one a lot so I want to dive into it further. Will one glass of wine or a beer or two throw off your morning temperature recording? Probably not. I rarely see this in my own cycle or work with clients, but it might so keep an eye on it. What I see more often is that a raucous night of indulging in more than many alcoholic beverages can definitely lead to wonky temperature readings.
WHAT IF I FORGET TO TAKE MY TEMPERATURE SOMETIMES?
Another complaint I hear a lot from prospective clients is “I’m never going to remember to take my temperature each morning.” That’s fair, forming new habits can be difficult. I recommend setting an alarm for the time you plan to take your temperature each morning. When the alarm goes off, roll over, pop your thermometer in your mouth, and wait the 60 seconds or so until it’s finished taking your temp. Then, roll over and go back to bed if you’d like. After a few months you may likely find that you don’t need the alarm clock at all anymore. I no longer use one.
Another option is the Temp Drop arm band thermometer which is designed to be worn on one’s upper arm as you sleep, then synced to your smartphone in the morning where it will output a temperature reading based on the core temperature recordings it was reading overnight. This device is also designed to filter out disturbed temperatures by learning the rhythms of your body with its built-in algorithm. It is one of the few fem-tech devices supported for the use of FAMs as birth control. While I have never personally used Temp Drop, or any fem-tech device for that matter, I do have many clients who enjoy using it. I will, however, implore you to turn off or ignore any information that Temp Drop may provide to you about which days of your cycle are fertile or infertile. We cannot know that with temperature information alone. We also need cervical fluid data and the rules of the symptothermal method for that.
CAN I USE THE OURA RING, APPLE WATCH, NATURAL CYCLES, ETC?
At the time of writing this post there are more and more fem-tech devices coming out every day that claim to accurately record temperature for fertility tracking purposes. Off the top of my head I know of the Oura Ring, the Apple Watch, Daysy, and Natural Cycles. I personally know folks who have attempted to use several of these devices as their birth control method without learning or applying the rules of the symptothermal method and experienced an unplanned pregnancy. This has less to do with the device’s ability to accurately track our temperatures and far more to do with the fact that they attempt to predict our fertile window’s opening and closing days by using temperature, past cycles, and algorithms alone - which does not work.
WHAT IF I WAKE UP A LOT DURING THE NIGHT?
This is one that I often hear from mothers with young children, nurses, and anyone who works shift work or suffers from insomnia. This is a case where I feel that using Temp Drop may be in our best interest. Because it is not time dependent and has an algorithm designed to field temperature disturbances, it can be a more reliable option for folks who have unpredictable sleep patterns. Ideally, though, unpredictable sleep is something that we would resolve, not only for more accurate FAM temperature tracking, but because consistent, quality sleep is vital to our overall health and wellbeing - including our menstrual cycles and fertility!
What type of thermometer DO you need to track BBT?
I don’t have a big long list of thermometers that I love for FAM tracking. Probably the most important thing to know when choosing a thermometer for FAM tracking is that it MUST be an oral, anal, or vaginal thermometer. Because I am a woman who doesn’t love sticking stuff up my butt or vag anymore than absolutely necessary, I have always used an oral thermometer and so have most of my clients. We cannot use the new forehead, ear, wrist, or those weird thermometer guns for FAM temperature tracking.
Next up, most FAM educators will tell you that you need an oral thermometer that reads out two decimal points. If that resonates for you, great. I, however, have never tracked out to the second decimal point and the charts that we use at Sauvage Wellness read to the first decimal point only. The OG fertility awareness methods book Taking Charge of Your Fertility by Toni Weschler also teaches temping and recording to just one decimal point. My thoughts - Choose your own adventure. I’ve seen the method be effective both ways.
Lastly, be sure to purchase a fertility, ovulation, or basal body temperature thermometer not a fever thermometer. Fever thermometers are not designed to measure as accurately as fertility thermometers.
Beyond these three main points, much of the rest is up to preference. Do you want a thermometer that stores your last recorded temp in case you forget what it was before you write it down? Do you want a little light on the thermometer screen so you can read it better in the dark? Do you want your thermometer to sync with your smartphone so that you can have all your temps easily stored in your phone? Do you feel more comfortable spending a lot of money on a thermometer or is your budget a bit tight? These are all up to you.
My general advice to my clients is don’t buy the cheapest thermometer you find, but also you don’t have to spend a ton of money. I feel that the sweet spot is around $20 or $30 USD. I also find that having a thermometer that stores your last recorded temperature is really helpful. My current one does not and it’s annoying. Other than that, I’m really not picky. Buy it online or get it at the drugstore, doesn’t matter. Two popular basal body thermometer brands here in the US are iProven and Easy@Home.
There you have it - a deep-dive, inside look at how to track temperature for birth control and fertility. If you’re interested in learning more about using the symptothermal double check method for birth control or pregnancy, I highly recommend checking out the following resources:
Schedule a free info call with me to chat 1:1. You can do that here!
Sign-up for my free cycle tracking mini-course - How To Cycle Track The Right Way For Birth Control, Pregnancy, & Better Periods. You can sign-up for that here! (You’ll just need to scroll down a bit.)
Check out my signature Cycle Wisdom Course. This is where I teach you how to use the symptothermal double check method all on your own in just 3 cycles! Learn more here.