The Natural Cycles app is a mobile application classified in the EU and by the FDA as a medical device for contraception. Technically it is a fertility awareness method or natural family planning, but we wanted to collect data on it separately as so many Lowdown users are interested in other women’s experiences using it.
How the Natural Cycles App works
The Natural Cycles app contains an algorithm that analyses your temperature (measured using a thermometer) and menstrual cycle data to calculate when you are fertile, and tells you to avoid sex or use other protection like condoms on your fertile days. Unlike other fertility awareness methods it tries to minimise human error as the algorithm does the calculations and interpretations.
To use Natural Cycles you need to pay for a subscription, download the app and buy a two decimal basal thermometer.
You will need to measure your temperature under your tongue every morning – measuring before you get out of bed at roughly the same time every day and after a similar amount of sleep. You enter this data along with your menstrual cycle data, into the app.
The algorithm in the app will determine your ‘fertile window’ and will tell you if you are on a ‘red day’ or a ‘green day’. You will need to use protection like condoms or abstain from sex on red days.
During your menstrual cycle your temperature rises and falls slightly which is due to the change in your body’s hormone levels. The Natural Cycles algorithm analyses your temperature (and optional LH test results) and also takes into account other factors like sperm survival, temperature fluctuations, and cycle irregularities to identify ovulation and calculate your red and green days.
The number of green days will increase as the algorithm gets to know your menstrual cycle, and it can take around three months of using Natural Cycles for the algorithm to be effective.
How to stop
Stopping using Natural Cycles is easy, you just stop using the app to record your temperature and menstrual cycle. As soon as you stop using it, you are no longer tracking your fertile days and may get pregnant if you have sexual intercourse.
Check out our survey results to learn about other women’s experiences using Natural Cycles.
Things that can go wrong
Check out the Natural Cycles website for all of their information and FAQs. Ultimately, you may have sex accidentally without protection when you are fertile and that could lead to pregnancy. It can take several months for the algorithm to be effective, and lots of factors (illness, lifestyle, stress or travel) may make fertility indicators harder to interpret.
You may forget to take your temperature or input your menstrual cycle data into the app. They recommend you measure your temperature at least five out of seven days a week. If you forget to enter data, the app will give you more red days.
You may accidentally have sex or not use protection on a red day. If this happens you may need to use emergency contraception.
Using hormonal emergency contraception will affect your normal hormone pattern and alter the algorithm and your number of red and green days.