Recently, we’ve seen more and more women speak out about their “not so great” experiences with hormonal birth control, with many opting for alternative, non-hormonal methods instead. 

Other than the copper IUD, we definitely have some work to do when it comes to lifestyle-friendly innovation within the non-hormonal birth control category.   

There are other non-hormonal options like the diaphragm, cervical cap, and sponge, but they’re all more high maintenance than other methods, including condoms, which is why most people avoid them.

So for the time being, we’ve seen more women opt for fertility awareness methods like the temperature and calendar method that help track their menstrual cycle and fertile days so they can prevent pregnancy (and get to know their body a bit better). 

And while these all sound great in theory, it still begs the question for most, “How accurate and reliable are these?”

The different kinds of fertility awareness methods 

Fertility awareness methods (otherwise known as “natural birth control”) help you track your menstrual cycle so you know when you’re ovulating, which is when your ovaries release an egg each month. Every woman’s cycle is different, but on average, ovulation happens around day 14 of your menstrual cycle (the halfway point).  

The days surrounding your ovulation window are your fertile days, which is when you’re most likely to get pregnant. For most women, they have around 6-7 fertile days, which are the 5 or 6 days leading up to ovulation, then the day of ovulation itself. This is because sperm can live in a woman's uterus for up to 5 days. 

Some women use fertility awareness methods so they can avoid sex or opt for other birth control methods like condoms during their fertile days. In general, fertility awareness methods are 77-98% effective when done correctly, which requires daily dedication and no sex (or sex with protection) on certain days. 

Here are the different fertility awareness methods that help you track your fertile days and point of ovulation: 

1. The temperature method (also known as the “rhythm method”)

The temperature method requires you to take your body temperature using an extra sensitive basal oral thermometer first thing in the morning before you get out of bed. Due to surges in estrogen and progesterone, your basal body temperature goes up by 2-4 degrees after ovulation.  

To use the temperature method effectively, you must take your temperature at the same time and in the same way every single day, then write it on a fertility awareness chart or input it into an app like Natural Cycles. You can get a chart from your doctor or a nearby family planning clinic like Planned Parenthood

You need to track changes in your body temperature for at least 3 months before you start reliably using it as birth control so you confidently know your personal patterns.

Certain factors like smoking, drinking alcohol, being jet lagged, sick, or stressed can all throw off your body temperature and give you a false reading. Keep note of these factors to help you figure out when these changes in your temperature aren’t part of your natural menstrual cycle.

2. The cervical mucus method 

The cervical mucus method helps you predict your fertile days by tracking changes in your cervical mucus (i.e. vaginal discharge) throughout your menstrual cycle. 

Your cervical mucus (the gooey stuff that comes out of your vagina as discharge) changes in color, texture, and volume throughout your menstrual cycle and especially during ovulation. 

To use the cervical mucus method for birth control, you have to feel and look at your mucus every single day after your period ends, then record what you see on a special cervical mucus chart. Like a BBT chart, you can ask your OBGYN for one or go to a nearby family planning clinic. 

To check your cervical mucus, you can: 

  • Wipe the opening of your vagina before you pee with white toilet paper or tissue, then check the color and feel of the mucus

  • Look at the color and texture of the discharge on your underwear

  • Put clean fingers into your vagina, then check the color and texture of the mucus on your fingers

The best way to analyze your cervical mucus is to rub it between your thumb and index finger. Unlike the temperature method, this can be done at any time of day. A cervical mucus chart helps you easily record everything you notice, based on the time of month. 

For example: 

  • Dry days = the 3-4 days after your period

  • Sticky days = before and after ovulation

  • Cloudy days = before and after ovulation

  • Slippery days = right before and during ovulation (usually lasts around 4 days) 

  • Period days = During your period you won’t notice any cervical mucus 

In general, it’s “safe” to have unprotected sex with a vetted partner during the 11-14 days after ovulation when your slippery mucus goes away and becomes cloudy and sticky. 

“Unsafe” days are your “slippery days” leading up to and during ovulation, the 2-3 days after your period ends (when you first start producing slippery mucus), and during your period (given you don’t know what your mucus looks or feels like). 

When you first start charting your mucus, use condoms for one full menstrual cycle since sex can make your body produce more or different kinds of mucus. 

Other factors that affect your cervical mucus include: using lube, douching, breastfeeding, hormonal birth control including the morning-after pill, STIs, vaginitis, early menopause, and specific medications.

3. The calendar method 

The calendar method, also known as the “rhythm method,” requires you to chart your menstrual cycle for at least 6 cycles on a monthly calendar so you can predict your fertile days in advance. You can do this with a standard calendar or an app like Flo, Clue, Cycles, Apple Cycle Tracking.

To use the calendar method, you mark the first day of your period (day 1) and the first day of your next period. Then, you count the total number of days in between (i.e. from day 1 to the following day 1). 

If your period is less than 27 days, you shouldn’t use the calendar method because it won’t be accurate. 

After you’ve recorded the start dates of your period for 6 cycles, find the shortest cycle and subtract 18 from the total number of days in that cycle. 

Take that final number and count it from day 1 of your current cycle and mark it with an X on your calendar. Be sure to include day 1 when you count. The day marked X is your first fertile day. 

To find your last fertile day, find the longest cycle from your 6-month record and subtract 11 from the total number of days in that cycle. 

Take that final number and count it from day 1 of your current cycle and mark it with an X on your calendar. Be sure to include day 1 when you count. The day marked X is your last fertile day. 

Because the calendar method can’t tell you exactly when you’re fertile and rather, can only predict when you’re most likely to be “safe” and “unsafe” to have unprotected sex with a vetted partner, it’s most effective when combined with other fertility awareness methods, like temperature and cervical mucus methods. 

4. The symptothermal method 

The symptothermal method is when you use more than 1 fertility awareness method in combination. 

​​Combining 2 or 3 methods into the symptothermal method is the best way to prevent pregnancy. Generally, people tend to use the temperature and cervical mucus method in tandem. Some go a step further and use the calendar method to double-check themselves. 

5. The standard days method 

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The standard days method is a variation of the calendar method, but you can only use it if your cycles are a specific length and consistently regular. 

Your cycle can’t ever be shorter than 26 days or longer than 32 days. You also have to be okay with either not having vaginal sex or using protection from day 8-19 of your menstrual cycle.

Simply put, the standard days method = abstaining from sex or using protection on days 8-19 of your cycle 

Most people who comply with the standard days method either use an app, map it on a calendar, or have CycleBeads, a special string of beads that help them keep track of which day they’re on. 

How effective are fertility awareness methods in preventing pregnancy?

The temperature method 

According to the American College of Obstetricians and Gynecologists (ACOG) around 5% of women will get pregnant when using a fertility awareness method like the temperature method with consistent, accurate tracking. Without “perfect use,” pregnancy rates can rise from 12 to 25%. 

ACOG doesn’t recommend using the temperature method alone to predict pregnancy because it only shows when ovulation has already occurred, not when it’s going to occur, and body temperature can be altered by various factors.

This is why combined use of the temperature method with the cervical mucus method and calendar method (i.e. the symptothermal method) is ideal because it maximizes effectiveness. 

That said, Natural Cycles reported their product (which leverages an algorithm to guide you on when you should use protection based on your basal body temperature changes) is 93% effective with typical use and 99% effective with perfect use because they’re able to predict in advance when you’ll begin your fertile days. 

The cervical mucus method 

With perfect use, the cervical mucus method can be upwards of 97% effective, however, it does require formal training to master the cervical mucus method to ensure you’re measuring changes on a daily basis appropriately. With typical use, meaning accounting for user error, it’s roughly 85% effective.  

This is why, similar to the temperature method, it’s recommended you combine multiple fertility awareness methods to maximize effectiveness. 

The calendar and standard days methods 

One study out of Germany in 2007 found that with perfect use, the calendar method can be upwards of 98% effective. However, with typical use, the effectiveness is estimated to be around 80% effective

The standard days method, a variation of the calendar method, is 88% effective with typical use and 95% effective with perfect use. 

If you’re using the calendar method to prevent pregnancy, it should ideally be combined with other approaches like the cervical mucus and temperature methods. When combined into a trio like this (i.e. the symptothermal method), effectiveness can rise to 95-99% with perfect use.

Caroline McMorrow is Rescripted's Content Manager.