www - I am not a fan of fertility awareness methods, as the failure rate is so high. All these methods rely on:
Having a regular cycle with no deviation in cycle length
Ovulating on the same day each month
The first is not the case for all women, and we can’t know the second without blood tests and scans, which clearly aren’t feasible.
Some women have always used this, by checking temperature, mucus, charting their cycle etc, and very very well motivated to do so, mainly for spacing babies, where pregnancy would jot be a disaster.
The popularity amongst young women currently panders to the “I don’t want to put hormones in my body” message. This is increasingly common, and of course ignorant of the fact that there are huge amounts of hormone whizzing round your body anyway. It implies that hormones are dangerous - yes there are some health risks with contraception (mostly oestrogen-containing methods), but these are remarkably few. Most of the other problems are side-effects, which can be managed, or changed to another method that suits better.
Most of these younger women don’t do anything to be aware of their own fertility, apart from not use any contraception or just withdrawal. I see lots of them, multiple times, in the termination clinic and with STIs, as condom use is not what it should be,
Sorry for the rant - but we are extremely lucky to have access to free contraception, and a degree of pragmatism is needed is finding the best method for you at that time, and sticking with it, in order to avoid multiple unplanned pregnancies.