Now we know better, you might think using fertility awareness as contraception means you only need to use condoms or other precautions for a few days each month.
Unfortunately that's not how it works. Even with loads of data about your cycles, and very regular periods, you need buffer days to allow for things changing from month to month.
At best, you can expect 9 to 11 red (fertile) days. It will be more than this while you are learning and if your periods are very irregular, or if you decide you'd rather only have unprotected sex on your green days.
If that's not right for you and your partner, then nor is fertility awareness.
The good news is those days do not have to be a terrible trial. Many couples appreciate the variety and many men pride themselves on acquiring that under-rated life skill of effective condom use.
Find out if fertility awareness is right for you here.