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If you’re looking for an alternative to traditional birth control, fertility awareness methods (FAMs) could be for you.

They’re a bit more complicated, yes. But they don’t involve any kind of hormonal treatment, meaning no unwanted side effects.

Instead, all they require is for you to monitor and record certain things in order to predict when you’re fertile and prevent pregnancy.

And thanks to the rise of fertility tracking apps, the symptothermal method is one of the most popular. Read on to find out what it is and how you can incorporate it into your life.

In a nutshell, according to Planned Parenthood, the symptothermal method is a combination of three fertility awareness techniques:

All FAMs rely on the idea that pregnancy can occur for only around 6 to 9 days of the menstrual cycle.

During this fertile window, you can abstain from penis-in-vagina sex or ensure you’re using a barrier method or other form of contraception.

Using more than one method — aka the symptothermal method — is said to help people better identify that window.

Using the temperature, cervical mucus, or calendar methods alone are less effective than using them together.

So, if you’re opting for a FAM, the symptothermal method is the way to go. However, you’ll need to follow the technique carefully for maximum effectiveness.

According to the American College of Obstetricians and Gynecologists, fewer than 1 to 5 people out of 100 will become pregnant during the first year of using a FAM perfectly.

This increases to between 12 and 24 people out of 100 with typical use.

Understanding how the symptothermal method works means understanding each of its three parts.


The temperature method works by tracking body temperature changes during the menstrual cycle.

To do this, you’ll need to take your temperature every day and note it on a chart or in an app.

It’s best to do this as soon as you wake up. Stay in bed and use a basal thermometer.

After a while, you’ll start to notice a slight change in temperature at certain points of the month —it’ll typically be lower at the beginning of a cycle and elevate during ovulation.

Days in which you can “safely” have P-in-V sex are after your temperature increase has held steady for at least 3 days. “Safer” days end when your temperature goes down before your period.

Cervical mucus

Vaginal discharge, or cervical mucus, also changes throughout your menstrual cycle.

So you’ll need to take a look at this every day and write down:

  • what it looks like
  • what it feels like
  • how much there is

You can do this by wiping with white toilet paper before you pee, looking at any discharge in your underwear, or inserting clean fingers into your vagina.

Typically, the body will produce more mucus in the days before and during ovulation.

After this period, there’ll usually be less mucus. It generally looks cloudy and feels sticky before gradually disappearing.

Those days are said to be your “safer” days for P-in-V sex without a barrier method or other form of contraception.

But when your period starts, make sure you use a secondary method of contraception since you won’t be able to see what your mucus looks like.

Having sex without a condom or other barrier method outside your expected fertile window doesn’t guarantee that you won’t get pregnant.


The third and final method involves charting how long your menstrual cycle lasts.

Simply jot down the first day of your period and the first day of your next one. Then count the number of days in between.

To get an accurate number, you’ll need to do this for at least 6 cycles.

So, when are you fertile and most at risk of pregnancy? Well, here’s where a little math comes in:

  1. Determine which is your shortest cycle from the past few months.
  2. Take away 18 from the total number of days that cycle had.
  3. Then, count that new total from the first day of your current menstrual cycle and mark it on your calendar.
  4. That marked day is the beginning of your fertile window.

Your last fertile day can be estimated by finding the longest menstrual cycle in your chart, subtracting 11 from the total number of days, and counting that total from the first day of your current cycle.

Ideally, you’ll need to track all of the above for a few months (at least 6 cycles if using the calendar method) before using it as a form of birth control.

So in the meantime, you’ll need another form of contraception, such as condoms.

And when you do start to rely on the symptothermal method, it’s also sensible to use a secondary form of contraception during your fertile window if you don’t want to refrain from having P-in-V sex.

Of course, you can use contraception each and every time you have P-in-V sex for extra peace of mind.

This method isn’t suitable for everyone, so it’s best to speak with a doctor or other healthcare professional before trying it out.

For example, people who don’t produce much vaginal discharge are typically unable to reliably use the cervical mucus method.

Short menstrual cycles generally make the calendar method inaccurate. Similarly, if your menstrual cycles differ from month to month, you may find the symptothermal method hard to use.

If you fall into the following categories, you’ll also need to be extra careful when using a FAM:

  • You’ve only just started having periods or have irregular bleeding.
  • You’re nearing menopause.
  • You’ve recently come off of hormonal birth control.
  • You’ve recently given birth, had a miscarriage, or had an abortion.
  • You’re taking medication that can affect your body temperature, cervical mucus, or menstrual cycle.
  • You’ve been told by a healthcare professional that pregnancy could be a health risk.
  • You have a sexually transmitted infection or have an increased chance of contracting one.

Unlike other forms of birth control, you don’t have to put anything in your body with the symptothermal method.

It also costs less. Your only expenses are a thermometer, a calendar, and potentially a backup method like condoms.

Some people also like this method because they’re able to learn a lot more about their body and may feel more in control.

As well as helping prevent pregnancy, the symptothermal method can be an effective way to plan for pregnancy.

Because this method helps you identify your fertile window, you’ll know when you have a better chance of becoming pregnant.

Plus, you’ll start to understand what’s “normal” for your body and more quickly notice any unexpected changes.

While there are none of the adverse side effects that can come with hormonal birth control, the main risk is the higher potential for pregnancy.

If you don’t closely follow the method and have P-in-V sex without a barrier or other form of contraception during your fertile window, it may not work.

And if you do decide to avoid P-in-V sex during your most fertile period, that could mean abstaining for up to 16 days a month.

To rely on the symptothermal method, you’ll need to have a deep understanding of your body. And each part of the method can take a while to crack before you’ll feel confident in using it.

Common advice is to chart at least 3 months using the temperature method, at least 1 cycle for the cervical mucus method, and at least 6 cycles for the calendar method.

So if you combine all of them, you’re looking at around 6 months before you’re ready to rely on this method to help prevent pregnancy.

The method can be quite complicated in general.

You have to be committed to tracking your temperature and cervical mucus every day, and you must either avoid P-in-V sex or use a secondary form of contraception on fertile days.

Plus, certain health and lifestyle factors can affect the things you’re trying to track, which may impact your results.

Temperature can be affected by:

  • illness
  • stress
  • smoking
  • drinking

Similarly, cervical mucus can change as a result of:

Penetrative vaginal sex can also alter the mucus your body produces —using condoms for your first cycle can help avoid any confusion.

It’s also worth noting that sometimes, you may not notice a clear pattern at all, making this method an unreliable form of birth control, per 2017 research.

Although the symptothermal method isn’t considered a “first-line” birth control method, the fact it doesn’t have any side effects may appeal to you.

But it can be pretty complicated to start out on your own. So, it may be best to learn the ropes from a qualified teacher. (A healthcare professional can direct you to one in your area.)

Once you know what you’re doing, carefully stick to the instructions to prevent pregnancy. And remember: always use a barrier method or other form of contraception during your fertile window.

Lauren Sharkey is a U.K.-based journalist and author specializing in women’s issues. When she isn’t trying to discover a way to banish migraine, she can be found uncovering the answers to your lurking health questions. She has also written a book profiling young female activists across the globe and is currently building a community of such resisters. Catch her on Twitter.