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.
To get the maximum amount of green days, and to help the algorithm narrow down your ovulation window as precisely as possible, we recommend adding five temperatures per week.
If you are a new user, and you struggle with getting 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 an Oura Ring. When wearing an Oura Ring, your temperature trends get 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 here.