The Rhythm Method and the Standard Days Method are fertility awareness-based contraception methods, and Natural Cycles is a digital birth control method. These methods have one thing in common: They rely on identifying the user's fertile window. However, they work in different ways, and their effectiveness varies.
Both the Rhythm Method and the Standard Days Method rely solely on period data to determine the fertile window, while Natural Cycles uses temperature data to detect the user’s ovulation in each cycle.
In a study comparing Natural Cycles to the Rhythm Method and the Standard Days method, we found that Natural Cycles is able to more accurately identify the fertile days in each cycle than the other methods, meaning that it was able to give more Green Days – on average 61% after 12 cycles when using both temperature and ovulation test data compared to 43% with the Rhythm Method and 58% with the Standard Days method.
Natural Cycles is also less likely to give a wrong Green (non-fertile) Day on the most fertile days of the cycle, the days before ovulation, and ovulation day itself. When both temperature and ovulation tests were logged, the likelihood of Natural Cycles giving a wrong Green Day on these days was 0% (with temperature alone, the numbers were 0.31% on the day before ovulation and 0.66% on ovulation day). In contrast, the Rhythm method had a 0.80% likelihood of giving a wrong Green Day on the day before ovulation and 2.46% on ovulation day, and for the Standard Days method, these numbers were 6.90% and 13.01%, respectively.
If you’d like to know more about this study, our Research Library has a summary of the results.