Oh my I have just read the complex rules for natural family planning. It’s no wonder were all told to use other forms of contraception and how teenagers can’t be bothered and get pregnant. It does help ttc though and shows how little time you have and if the other half is constantly away at that time you do have to wonder whether they still want one or not. It also shows what happens when you have sex too late and that mucus usually indicates fertility but you can have spotting when you think it’s a period and your body is just doing a stress cycle. Ttc says 6-21 days of your cycle but if you were avoiding you would usually stop at 6-8 and restart at 17-18. The reason for most surprise pregnancies is you encroach on early fertility.
There is a society for the involuntarily childless which I was quite interested to find as I didn’t think that many people couldn’t have children. I must be a sign of the times that our population has grown so much we have a lot of faulty genes around. Possibly the environment also causes them along with many other aspects. Society is changing and I don’t know if we can do anything about that.