How Natural Cycles is Different to the Rhythm Method

One of the questions we’re often asked is ‘what makes Natural Cycles different from the rhythm method?’ In fact, there are a number of key differences that separate our contraceptive app from this method of birth control. Read on to discover how the rhythm method works, how Natural Cycles works, and the scientific research which is at the forefront of our work in women’s health.

A red and a green circle with the text 'Natural Cycles finds fertile days more accurately'

What is the rhythm method?

Before diving into what makes us different – let’s first look at what the rhythm method is and how it works. The rhythm method, or the calendar method, is a fertility awareness-based method of birth control that’s been around for a very, very long time. Its fertility calculations are based around menstruation dates, with women following the method using another method of birth control, or abstaining from sex, on the days they are predicted to be fertile. The rhythm method also involves a 6-month monitoring window before the method can be used. 

The rhythm method does take into account changes in the menstrual cycle, but this is only calculated at the end of each cycle, so it does not take into account changes day-to-day which can be factored in when monitoring basal body temperature. With perfect use (i.e. no human error and following the 6-month monitoring period), the rhythm method is 91% effective. With typical use (including errors from both users and the method itself) the rhythm method is considered to be between 75% and 88% effective. It’s also worth keeping in mind that, traditionally, the rhythm method required manual calculations which is time and labor intensive, requiring extra dedication and motivation from users of the method. 

What is Natural Cycles?

Natural Cycles is the first and only FDA Cleared digital birth control. It’s a birth control app that gives daily fertility statuses throughout your cycle in the form of red (fertile) days and green (non-fertile) days.

There are two important features that make Natural Cycles different from the rhythm method. Firstly, the app uses basal body temperature data. Due to our hormones, our body temperature changes over the course of the menstrual cycle, with a low but significant rise around ovulation day. Because these shifts in temperature happen while we are fertile (making it often too late to prevent pregnancy), there is another important part in Natural Cycles’ design that comes into play: the smart algorithm. This technology learns the pattern of your cycle so it can predict the fertile window ahead of time. 

This makes Natural Cycles a method which is very much tailored to each individual, and is an important factor in the effectiveness of this birth control method. With a more tailored method, the margins for error in the method can be reduced – and since the algorithm does the hard work, there is no need for manual calculations or charting. Natural Cycles has a perfect use effectiveness of 98% and a typical use effectiveness of 93%. 

So, how are Natural Cycles and the rhythm method different?

Here at Natural Cycles we have a dedicated research team who make it their mission to broaden knowledge around women’s reproductive health. Our latest study looked at the accuracy of the rhythm method and the standard days method (another fertility awareness-based method) in comparison to the Natural Cycles algorithm. The study was published in The European Journal of Contraception & Reproductive Healthcare, analyzed data from over 42,000 women. 

So what did the study find? Well, in terms of accuracy of finding the fertile window, the study discovered that using Natural Cycles’ algorithm, in comparison to the rhythm method, reduced the likelihood of receiving a wrong non-fertile day on the most fertile days by 69%. With the standard days method, this was even lower, with the likelihood of receiving a wrong non-fertile day dropping by 97% when using Natural Cycles instead of standard days. 

Not only was the accuracy between these methods significantly different, we also found that the number of non-fertile days given by the methods differed too. Natural Cycles and the standard days method both gave a similar number of non-fertile days (56% and 58% on average), while the rhythm method only gave 17% during the first year of use. 

What does this mean for preventing pregnancy?

A successful experience using Natural Cycles, the rhythm method or the standard days method relies on a low number of wrongly given fertile days as non-fertile, while still also giving as many non-fertile days as possible, so that the method offers user satisfaction. (This means being able to have unprotected sex on those days given as non-fertile.) Our study shows that the risk of being given wrong non-fertile days with these two fertility awareness-based methods are much higher, and in fact, with the rhythm method, you will receive far fewer non-fertile days overall. 

This means the risk of an unwanted pregnancy increases for those using the rhythm method (or a period tracker using this science) to find their fertile window. While, at the same time, the overall user experience may also be reduced. However, the good news is that basal body temperature data used by the Natural Cycles’ algorithm provided higher accuracy when giving non-fertile days, and a better experience for the user overall. This is great news for those of us looking for an effective method of birth control without using hormones – and means we can separate ourselves from these outdated methods and from those period tracking apps that are based on these static concepts. 

We hope you’ve enjoyed reading about how the rhythm method works, what makes Natural Cycles different and the research behind the first and only birth control app. If you’re looking for a hormone-free method of birth control that learns your unique cycle, look no further. Find out Natural Cycles could be the best birth control method for you and sign up online today.

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Written By

Jennifer Gray

A writer with a passion for women’s health, Jennifer Gray has years of experience writing about various reproductive health topics including birth control, planning pregnancy, women’s anatomy, and so much more.

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Scientifically Reviewed

Jack Pearson

With 10 years of experience working in the field of fertility, Jack Pearson is Natural Cycles’ in-house expert. As Medical Affairs Manager, he dedicates his time to conducting groundbreaking research and educating healthcare professionals.