If you sometimes forget to measure your temperature with a basal thermometer this will not affect Natural Cycles’ effectiveness as birth control. If the algorithm does not have enough data due to a lack of temperatures to support that you are not fertile on a given day, that day will be red (you will need to use protection).
If you skip a lot of temperatures, this will make it harder for the algorithm to identify your fertile window. As a result, you will get more Red Days (for NC° Birth Control) or Brown Days (for NC° Plan Pregnancy), which may reduce your satisfaction with the app.
We recommend adding five temperatures per week to get the maximum number of Green Days and help the algorithm narrow down your ovulation window as precisely as possible.
If you are a new user and struggle to get in the habit of measuring your temperature as soon as you wake up, do not get discouraged! Just like with any new habit, it may take some time before measuring becomes second nature. We have linked here tips on remembering to measure your temperature.
Note: If you are struggling with your measuring routine, know that you now have the option to use Natural Cycles with one of our approved wearable devices (the Oura Ring and the Apple Watch). When using Natural Cycles with a wearable device, your temperature data gets measured overnight while you sleep. This means that you no longer need to remember to take your temperature before getting out of bed in the morning! Learn more about using Natural Cycles with the Oura Ring here and with the Apple Watch here.