Natural Cycles differs in many ways – including how it works, how one should use it, and how effective it is. Natural Cycles, as well as the rhythm method, uses your body’s natural signs in order to identify your fertile days. Natural Cycles uses your unique basal body temperature and when your temperature has risen enough to confirm ovulation, the most probable ovulation day will then be confirmed according to the temperature curve.
Natural Cycles’ effectiveness rate of 93% with typical use and 98% effective with perfect use. Natural Cycles uses a smart algorithm that performs the analysis of your data and gives you either a green day, when no protection is needed, or a red day, when you should use a barrier method (such as a condom) or abstain from sex in order to effectively prevent a pregnancy. The Natural Cycles’ algorithm has been intricately designed to account for sperm survival, variation in cycle length, ovulation day, temperature fluctuations, and the length of the follicular and luteal phase.
The rhythm method (also known as the calendar method), fertility awareness method (FAM/FABM), or natural family planning (NFP), works by tracking menstrual history to predict when you will ovulate. This was historically performed by charting on paper and now often behind fertility tracking apps.