One of the most common myths about the Fertility Awareness Method (FAM) is that it doesn’t work to prevent pregnancy. And when women are learning how to use it they always want to know how effective it is. At perfect use, it’s 99.6% effective — as good as hormonal contraception! (something a lot of people don’t know).
So how do we know this? Science! Keep reading to see the research that backs this up.
When you read about the effectiveness of FAM, be sure to check and see what method specificially they are evaluating. One of the problems with how these methods are reported is that they are all lumped in together and the range given for effectiveness includes all methods and all studies. But there are multiple types of fertility awareness based methods and they are all slightly different, so comparing them all together is a mistake. For example, the Rhythm Method really does not work, but symptothermal methods are highly effective.
If you want to know how good your chosen method is, you need to find research specifically on that one method and ignore the rest.
So where does the number 99.6% come from? This is the result of a study done in Germany that looked at 900 women contributing 17,638 menstrual cycles! That’s a lot of data!
Women in this study were using the symptothermal method of FAM, which means they use symptoms of fertility (cervical mucus) as well as thermal measurements (basal body temperature). These are the same signs of fertility that the Justisse Method I teach uses.
Women in this study were all taught by accredited teachers from a German Natural Family Planning organization. Because of this they know that everyone was taught in a standardized way and they were able to know that each woman had the same level of knowledge. This also means that their results included women who were new to the method and just beginning to learn it.
One of the best things about this study is that they compared the pregnancy rates for cycles where different methods were used to avoid pregnancy during the fertile time: abstinence (no sexual intercourse at all), protected intercourse (barrier methods), and genital contact or withdrawal.
We consider you to be using FAM for contraception when you use abstinence during the fertile time, as that is how the method is designed.
In this study, the highest efficacy was found among those that used abstinence (0.4 pregnancies per 100 women; 99.6% effectiveness).
Conclusion: using FAM for contraception has a 99.6% perfect use rate!
It’s important to keep in mind that if you are using another method of contraception, such as barriers or withdrawal, you are no longer using FAM, instead you are using whatever other method you are using. In these cases, you have to assume that your chances of pregnancy are those of that particular method. See a list of methods and effectiveness here.
Interesting to note is that they found no statistically significant difference between these cycles and the cycles where barriers were used (0.6 pregnancies per 100 women; 99.4% effectiveness). Women using withdrawal had a rate of pregnancy at 1.2 per 100 (98.8% effective). Again, this is one particular study, with one particular group of women, so it’s best to assume your chance of pregnancy is that officially given for that method (see here).
Keep in mind the difference between perfect use rates and typical use rates. Typical use rates are lower, because they include the fact that women make mistakes, get confused, misunderstand, get lazy, become ambivalent, etc. resulting in a higher chance of pregnancy. But, if you are vigilant and follow the rules, you can achieve an efficacy rate as high as hormonal contraception!
Read the study and all the details for yourself here.
Knowing the science behind FAM certainly can be a comfort, and I will explore exactly how this works in future posts. Often even if we know the science, getting our minds and emotions around it can be more challenging. What has your experience been learning FAM? Were you concerned about the efficacy? How long did it take you to become comfortable using it and trusting it after first learning? Let me know in the comments below.