Natural Cycles App

What the packet says

What is it?

What's it made of?

Natural Cycles app is a mobile application classified in the EU and by the FDA as a medical device for contraception. Technically it’s a method of natural family planning, but we wanted to collect data on it separately as so many Lowdown users are interested in other womens’ experiences using it.

How it 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 telling you to avoid sex or use other protection on your fertile days. Unlike other fertility awareness methods it tries to minimise human error as the algorithm does the calculations and interpretations.


  • During intercourse
  • Daily
  • Monthly
  • 1 - 3 Months
  • 1 - 3 Years
  • 3 - 5 Years
  • Permanent
  • Clinical effectiveness



    Contains hormones


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    Detailed information

    How to get started

    • 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 period cycle data, into the app.
    • The algorithm in the app will determine your fertility status 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 thereby calculate your red and green days.
    • The number of green days will increase as the algorithm gets to know your fertility cycle, and it can take around three months of using Natural Cycles for the algorithm to become more 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’re no longer aware of when you are fertile and are therefore can get pregnant.
    • Natural Cycles has little to no after effects, but check out our survey results to learn about anything women have experienced.


    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 upset your normal hormone pattern and alter the algorithm and your number of red and green days.


    Natural Cycles App
    This method takes some commitment, as you need to remember to take your temperature as soon as you wake up, and it also ...
    Natural Cycles App
    I LOVE natural cycles. It has no side effects (obviously because I’m not putting anything in my body and I’m relying...
    Natural Cycles App
    Honestly after being on the pill for 3 years (various types) I am never going back. Natural cycles app takes an algorith...
    Natural Cycles App
    I really liked being on the natural cycle app. It was great for tracking periods (which were always on time) and for uti...
    Natural Cycles App
    Overall I did like Natural cycles. I liked learning more about my cycle and the app was easy to use. You also get used t...
    Natural Cycles App
    I was unhappy with the contraceptive pill so switched to natural cycles. Although it takes a few months for your periods...