What are fertility awareness methods?

What are FAMs?

Fertility awareness methods (FAMs) are a group of natural birth control methods that rely on identifying the fertile window in the menstrual cycle — this is the six-day window when it’s possible to become pregnant from having sex. These methods are sometimes also referred to as “natural family planning".

As the name suggests, fertility awareness involves understanding when in your cycle you are fertile and can get pregnant. This is done by monitoring certain fertility signs, such as basal body temperature or cervical mucus, that can show where you are in your cycle and when you’re ovulating. By learning to interpret these fertility signs, you can work out when you’re fertile, so you can choose to either use protection or avoid having sex on those days if you’re looking to prevent pregnancy. 

If you’re planning a pregnancy, you can also use fertility awareness methods to time sex on the days with the highest chance of getting pregnant.

What are the fertility signs during the menstrual cycle?

To be able to read the fertility signs and understand when we can and can’t get pregnant, we first need to know a bit about the basics of the menstrual cycle. The key to fertility awareness is knowing that you can’t get pregnant during the whole menstrual cycle. In fact, we’re only fertile for six days — this fertile window consists of the five days leading up to ovulation (due to sperm survival) and ovulation day itself. Therefore, estimating ovulation is crucial to knowing when you’re fertile!

The menstrual cycle is driven by changes in hormone levels (mainly estrogen and progesterone), and this leads to certain things happening in our bodies at specific times in our cycle. Fertility awareness methods work by tracking those fertility signs that tell us where we are in our cycle, including:

• Period dates: Each cycle starts on the first day of our period, so keeping track of your periods lets you know how long your cycles are. Because ovulation happens roughly two weeks before your next period starts for the average woman, this gives you an idea of when you might ovulate in your cycle. However, it’s important to keep in mind that cycles aren’t always the same length and that the ovulation day may vary — even if your cycles are usually regular, anyone can experience irregular cycles from time to time. 
• Temperature: Our body temperature and ovulation are closely linked. After ovulation, increasing progesterone levels cause the body temperature to rise slightly [1]. By tracking your basal body temperature throughout your cycle, you can know if and when you ovulate. 
• Cervical mucus: Cervical mucus, or discharge, changes throughout the menstrual cycle. During the fertile window, you may notice that your discharge becomes more stretchy and slippery. This consistency is what helps sperm stay alive for up to five days in the female reproductive system, and it also helps them reach the egg. After ovulation, the cervical mucus dries up again [2]. 
• Cervix position: Did you know that your cervix changes positions during the menstrual cycle? During your period at the beginning of the cycle, the cervix position is lower and it feels firm to touch. During ovulation, the cervix rises to a higher position and also feels softer. After ovulation, it begins to drop down to the lower position again [3]. When tracking cervix positions, it’s important to keep in mind that we’re all different, so some of us have a naturally higher or lower cervix — the key is figuring out how your cervix feels at different times of your cycles, and that can take some practice!

How do fertility awareness methods work?

There are a few different methods that fall into the fertility awareness category. These all have in common that they rely on the user to interpret their own fertility signs during the menstrual cycle to figure out when they are fertile. During those fertile days, you then need to either use additional protection, such as a condom, or abstain from intercourse to prevent pregnancy. During days when you’re not fertile, you can have unprotected sex without fear of pregnancy. However, keep in mind that you should always use a condom to protect from sexually transmitted infections (STIs) if you’re at risk.

Learning to interpret fertility indicators like temperature or cervical mucus takes time and effort, and is best learned with the help of a healthcare professional who specializes in fertility awareness. Most FAMs also require an initial monitoring period before they can be used to prevent pregnancy since you typically need to track several cycles before learning your individual patterns.

What different kinds of fertility awareness methods are there?

Even though they are often lumped together, fertility awareness methods or natural family planning is not just one method. Let’s walk through some of the big ones!

The calendar method

Calendar methods rely on tracking periods and counting cycle days to determine the fertile days in the menstrual cycle, usually with the help of a calendar or a cycle-tracking app. 

While there are some variations of calendar methods out there, the most well-known is called the rhythm method. To use it, you first need to monitor your periods for at least six cycles and count how long each cycle is. You’ll need to use additional protection during this time, and only after those six cycles of monitoring can you start calculating your fertile days using this method [4]: 

1. To find the start of your fertile days, take the number of days in your shortest cycle and subtract 18. For example, if your shortest cycle was 27 days, your fertile days would start on cycle day 9.
2. To find the end of your fertile window, take your longest cycle and subtract 11. If your longest cycle was 30 days, that means your fertile window ends on day 19.
3. Continue tracking your periods and update your calculations as needed.

There’s also another type of calendar method called the Standard Days method, which works a little differently. It’s a simplified version of the rhythm method but instead of the window moving, the same days are always considered fertile (days 8-19). The Standard Days method can only be used if your cycles are very regular; they always need to be between 26 to 32 days, and if you have cycles that are longer or shorter than that, you’re not recommended to use this method [5].

Calendar methods rely on simplified assumptions about the menstrual cycle to determine the fertile days, for example, that ovulation happens roughly 14 days before the start of the next period. However, that’s not always the case in real life — in a study of over 600,000 cycles logged on Natural Cycles, we found that ovulation happens on average 12 days before the start of the next period [6]. That means that the calculations used by calendar methods risk missing a number of fertile days for many people, especially those with more irregular cycles [4].

The cervical mucus method

Our cervical mucus changes during the menstrual cycle, so if you know what you’re looking for, it can give a lot of information about your fertility. Tracking your cervical mucus to predict fertility is also called the Billings method or sometimes the ovulation method. Some also combine cervical mucus tracking with monitoring their cervix position. These are the basics of how to use the cervical mucus method [7]: 

1. Keep track of the amount, color, and consistency of your cervical mucus every day of your cycle. 
2. Stop having unprotected sex as soon as you notice cervical mucus is present. Right after our period ends, we usually don’t see much cervical mucus. It then becomes more abundant before ovulation as we enter the fertile window, taking on a more slippery consistency similar to egg whites. 
3. After ovulation, cervical mucus dries up again and gets a more creamy consistency — then it’s safe to have unprotected sex again according to this method.

It’s best to learn how to track cervical mucus with the help of a fertility specialist or other healthcare professional since it can be tricky to get it right, and you need to monitor it for at least a month before you can rely on this method to prevent pregnancy. Even then, this method is only 77% effective with typical use [8]. It’s also important to keep in mind that many things other than the menstrual cycle can mask cervical mucus, such as sexual arousal, lubricants, discharge from infections, and more [7].

The temperature method

The temperature method involves measuring basal body temperature during the menstrual cycle and keeping track of it using a chart. Because there is a small but significant shift in temperature after ovulation due to the higher progesterone levels, it’s possible to know when you ovulate by following the temperature curve during each cycle. Here’s how to use the temperature method:

1. Measure basal body temperature daily. You need to take your temperature every day using a thermometer that measures with two decimals, at the same time every day and right as you wake up in the morning (before sitting up or getting out of bed).
2. Chart your temperatures. Your temperature will be lower during the follicular phase of the menstrual cycle. Once you ovulate, your temperature rises by between 0.5 and 1 °F (0.3-0.6 °C) and stays elevated for the rest of the cycle before it drops again right before your period starts. 
3. Use protection on days you may be fertile. You should use protection from the start of your cycle until you can confirm that you’ve ovulated. Once your temperature has stayed elevated for at least three days, you can have unprotected sex until your next cycle starts. 

It may be helpful to get help from a healthcare professional when you start tracking temperatures so that you know what to look out for in your temperature curve. You need to track temperatures for at least three cycles before you can use the temperature method to prevent pregnancy since you need to learn the pattern of your cycle first. In addition, your temperature is also affected by sleeping much more or less than usual, drinking alcohol, and being sick, so you shouldn’t use your temperature on days when those circumstances apply.

If you don’t want to calculate your fertile days yourself, Natural Cycles combines temperature tracking with an algorithm that calculates your ovulation and daily fertility status for you, taking the manual charting and guesswork out of the equation! The effectiveness of Natural Cycles does not change if you forget to measure and there is initial no monitoring period required.

The symptothermal method

You can also combine these fertility awareness methods and track your menstrual cycle using several fertility indicators at once. Specifically, tracking temperatures along with other fertility signs like cervical mucus is called the symptothermal method.

Tracking cycles this way is often more accurate than using individual fertility indicators since you have more information to go on, and the symptothermal method is the most effective FAM with a typical use effectiveness of 98% [8]. However, it’s good to keep in mind that this method requires a lot of input from those using it — you must monitor a number of fertility indicators daily and chart and record the readings yourself. For this reason, the symptothermal method is considered too cumbersome by many.

How effective are fertility awareness methods?

The short answer is that it depends on which method we’re looking at. Most fertility awareness methods are generally not considered very effective as birth control, but the range is actually quite large. Depending on the method, the effectiveness with typical use ranges between 77% and 98% effective, which means that 2-23 out of 100 women per year who use these methods become pregnant [8]. 

One of the reasons that these methods tend to be less effective with typical use (meaning how a method is used in real life) compared to other types of birth control, like the pill or IUD, is that they require a lot of work from the user, which leaves a lot of room for human error. For example, it’s easy to misinterpret cervical mucus since it can vary from person to person and even from one cycle to the next.

There are also some factors that are built into the methods themselves that can make them unreliable for some people. The calendar method, for example, can work well for those with very regular cycles where ovulation tends to happen on the same day each cycle. However, our bodies aren’t machines, and our menstrual cycles aren’t always regular. Calendar methods don’t always adjust for the fact that ovulation may happen earlier or later than usual. Natural Cycles, on the other hand, takes into account each user’s individual ovulation pattern and how it changes.

How can I make fertility awareness methods more effective?

Birth control methods are most effective when you follow the instructions exactly and at all times, and fertility awareness methods are no different. While typical use effectiveness ranges from 77-98%, the perfect use effectiveness is higher, at 95-99%, depending on the method [8]. 

Fertility awareness methods will be the most effective when:

• You consistently track your fertility signs every day
• You and your partner always use protection (or abstain) on days when you may be fertile
• You learn how to use the method from a healthcare professional, such as a doctor, nurse, or fertility specialist who is trained in FAMs and can help you get up and running
• You use more than one fertility sign to track your cycle

You can also consider using Natural Cycles, the first and only FDA Cleared birth control app. Natural Cycles’ algorithm uses temperature data along with period data and optional ovulation tests to calculate your daily fertility status. When compared to calendar methods (the rhythm and Standard Days methods) Natural Cycles is more accurate when it comes to finding the fertile window, making it less likely to give the user an incorrect safe (non-fertile) day when they are actually fertile [9]. NC° Birth Control is 93% effective with typical use and 98% effective with perfect use. 

Pros and cons of using FAMs

All birth control methods come with their own set of advantages and disadvantages, and fertility awareness methods are no different. On the plus side, some pros of using these methods are:

• You learn about your body and cycle
• They have no side effects 
• They are non-invasive (you don’t put anything in your body)
• No prescription is needed
• They are low-cost 

On the other hand, fertility awareness methods aren’t suitable for everyone. Those with irregular cycles (very short or long cycles, or cycles that vary in length) shouldn’t use FAMs since it’s more difficult to predict fertility if cycle length varies a lot. Similarly, you’re not recommended to use fertility awareness methods as contraception if you have certain medical conditions, such as PCOS or certain thyroid conditions, that affect the menstrual cycle. Some other cons of these methods are:

• In most cases, FAMs are less effective than many other birth control options
• They require a lot of dedication since you need to track your fertility signs every day
• You need to use other protection or abstain from intercourse on the days you may be fertile for the methods to be effective
• They don’t protect against STIs 

Natural Cycles is more than a fertility awareness method

At Natural Cycles, we believe that the most important thing about contraceptive choice is having access to information so you can make an informed decision about which method best suits your lifestyle, as there is no one-size-fits-all when it comes to birth control. The first of its kind to be FDA Cleared in the US and CE-marked in Europe, Natural Cycles is more than a fertility awareness app — it’s a certified and regulated birth control method. Additionally, you can use it to plan a pregnancy if and when you’re ready.

Natural Cycles’ algorithm learns your unique cycle based on body temperature, period data, optional ovulation tests, and other factors such as recent use of hormonal birth control. Because it adapts to each individual, Natural Cycles is just as effective for those with irregular cycles, and it’s effective from day one so no initial monitoring period is required. You can choose to measure with a basal thermometer or opt for one of our integrated wearables, Oura Ring or Apple Watch, to measure seamlessly overnight. 

Simply log your data in the app, and the algorithm will give you your daily fertility status — either a Green Day (not fertile) or Red Day (use protection) — taking out the guesswork. In addition, you can keep track of other fertility signs, such as cervical mucus, moods, and more, to get to know your body. Why not find out if Natural Cycles is a good fit for you?