If you don’t get any periods, we don’t recommend using Natural Cycles, as the algorithm wouldn’t be able to analyze your cycle, and you would only receive Red Days. Your period marks the start of a new cycle and is one of the key indicators the algorithm uses to calculate your fertility status.
Even if you still ovulate (for instance, if you had a hysterectomy but still have your ovaries), the algorithm would not be able to identify your fertility status without period data to differentiate between your cycles.
You can learn more about how Natural Cycles works here, and you will find more information on Natural Cycles and the menstrual cycle here.
Note: if you have periods but they are very irregular, you can check our article on using the app with irregular cycles