Symptothermal Fertility Awareness Method
Recently I had an exchange on X with several people who were arguing with me about the fact that the symptothermal fertility awareness method (sFAM) works just as well as hormonal birth control, condoms and other commonly used methods for family planning.
In the thread, I was accused of lying, and there was a misconception from several users that the rhythm method (which does not work) is the same thing as the symptothermal fertility awareness method, which it’s not. Unlike the rhythm method, the symptothermal method is evidence-based, works just as well as hormonal methods, and is free from side effects or risks to health. It’s also extremely low cost and gets you more in touch with your body.
I am in no way shaming those who choose hormonal options in full informed consent. It is definitely more work than popping a pill or going to the Dr every 7 years to swap out your plastic implant. As US citizens, we have the legal right to full informed consent which includes knowing about all alternative options. It’s my view that true informed consent is RARE in the US, and not just with this type of drug.
What is the Symptothermal Fertility Awareness Method?
The symptothermal method is a scientifically supported form of fertility awareness that involves tracking multiple signs of fertility to determine the fertile window within a woman’s menstrual cycle. These signs typically include daily basal body temperature (BBT), changes in cervical mucus, and sometimes cervical position. By cross-referencing these biological indicators, the symptothermal method allows for precise identification of ovulation and is used either to achieve or avoid pregnancy. When practiced correctly and consistently, it has a typical-use effectiveness comparable to hormonal birth control or condoms, making it a highly reliable natural method for family planning.
The “Rhythm” Method
In contrast, the rhythm method—also known as the calendar method—is an outdated and largely discredited approach that relies solely on past cycle lengths to predict future fertile windows. It assumes a woman’s cycle is consistently regular, using mathematical estimates (like ovulation occurring on day 14 of a 28-day cycle) rather than real-time biological signs. Because it ignores the natural variability in menstrual cycles and does not adapt to irregularities or changes in ovulation, the rhythm method has been shown to be ineffective and is no longer recommended by most health professionals. Importantly, it should not be confused with the symptothermal method, which is based in real-time physiological observation, not guesswork.
Most period tracking apps available today are operating with the Rhythm/Calendar method and don’t even have the option to track enough of these biomarkers so the “fertile window estimates” are not reliable for preventing pregnancy.
Why It Matters
This is so important to me because hormonal birth control does have side effects and risks. It’s a known carcinogen at the same level as cigarettes or asbestos, not to mention the risk of weight gain, emotional and mood disorders, acne, and other health conditions.
Knowing how to track your cycles and control your own fertility without risking your health is empowerment. The symptothermal method is evidence-based and hormone-free, so especially if your cycles are pretty regular I feel it’s a no-brainer to use this instead of risky hormonal treatments. Even the plastic/copper IUD has a class action lawsuit going on right now.
There are tons of studies like this one showing the effectiveness of sFAM in the book Taking Charge of Your Fertility by Toni Weschler
How to Track Your Biomarkers
When starting out tracking, I recommend that you observe and learn about your unique patterns for a few months before putting full trust in the symptothermal method. Once you learn what your fertile signs look like, it’ll be relatively easy to tell if you’re fertile or not. Get into the habit of tracking these daily, and you’ll always have an idea of your fertility.
1—Basal Body Temperature (BBT)
Basal body temperature is your body’s lowest resting temperature, taken first thing in the morning after at least 3–4 hours of uninterrupted sleep. To track it, use a digital basal thermometer (accurate to two decimal places) and take your temperature at the same time each day before getting out of bed or even speaking. Record the reading on a chart or app. After ovulation, progesterone causes a noticeable rise in BBT—typically about 0.5°F (0.3°C) or more. This shift confirms that ovulation has occurred. You are considered infertile beginning the third day after this sustained rise, provided it aligns with other fertility signs.
2—Cervical Mucus
Cervical mucus changes in consistency and appearance throughout the cycle, reflecting hormone levels and fertility. Begin checking mucus daily from the end of your period by wiping front to back with clean toilet paper or fingers before urination. You may observe dry days, sticky or creamy mucus, or stretchy, clear “egg-white” mucus. Fertile-quality mucus is slippery, abundant, and indicates that ovulation is near or occurring. Infertile days are typically dry or have thick, tacky mucus. Track the type, amount, and feel each day, and interpret patterns over time to identify your fertile window.
3—Cervical Position (Optional)
The cervix also changes position and texture throughout the menstrual cycle. With clean hands, insert one or two fingers into the vagina daily around the same time to assess its position and firmness. During non-fertile phases, the cervix is lower, firmer, and closed. As ovulation approaches, it rises higher, softens, and opens slightly to allow sperm to pass through. Tracking cervical position can be especially useful when used alongside BBT and mucus, though it is considered optional and may take a few cycles to interpret reliably.
Taking Charge of Your Fertility
I highly recommend getting the book Taking Charge of Your Fertility by Toni Weschler (affiliate link) for instructions and troubleshooting and general information on understanding the fertility signs in your body. She goes deep with the descriptions and how to for all of this, studies, and more.
My mom gave me this book when I hit puberty and it’s had such a huge impact. I’ve recommended it to countless friends who have all said it really helped them understand the inner workings of their body’s reproductive system.
The book also features charts that you can photocopy (or download for free from TCOYF website) to track your biomarkers.
How to Track
Every month as you track your waking basal body temperature, you’ll notice around halfway through the moth (for most women), there is a dip in basal body temperature. This is indicative of ovulation. You’ll still want to monitor other signs as well to double check your work, but this is one of the best indicators that you’ve ovulated.
Keep in mind that egg-white consistency cervical mucus keeps sperm alive for up to ~5 days or so. This means that if you have the egg white consistency and have unprotected sex, if you end up ovulating within 5 days or so after that, you could get pregnant. Tracking your cervical mucus daily at the same time (without being aroused) is so important. Also, if you were intimate the night before, do kegels afterwards to clear out lingering moisture so that you can get a clear reading the following morning.
Thermometers
So there are a few different types of thermometers out there, and not all of them will work for tracking your fertility. You need one that is specifically labeled as a “basal body temperature thermometer”, otherwise it will not be precise enough to track accurately.
You’ll need to keep it under your tongue for 1-5 minutes as soon as you wake up, before getting out of bed or talking, at the same time every morning. Any movement will raise your body temperature, so it’s best to measure as quickly as you can without moving too much.
Cervical Mucus
At the same time each day, and with clean hands, put 2 fingers up there and do a circular swipe around the cervix, then remove your fingers and observe the consistency of the mucus. If it’s dry, and not stretchy at all, you’re probably not fertile right now. If it comes out stretchy or egg-white consistency, this is a sign that you are likely fertile right now and will likely ovulate within the next few days.
It may help to do this while squatting or with one leg up on a surface to better reach, especially if your cervix is in a higher position.
Cervical Position (Optional)
As you are checking the cervical mucus, notice the position of your cervix and document that on your chart. During non-fertile phases, the cervix is lower, firmer, and closed. As ovulation approaches, it rises higher, softens, and opens slightly to allow sperm to pass through.
What If Your Cycles are Irregular?
You can totally still track your markers, it just requires more strict accuracy. If your cervical mucus is not wet/viscous, there is no medium for sperm to live in or swim through to access the egg. Keep in mind that the range of normal physiology is very wide, and even if your cycles are atypical, you can still track and find success with this method.
