Nice post! Controversially interesting. Lolz....
I think option 5 should be "MONTHLY CALCULATIONS AND PERMUTATIONS." That also works. If both partners are aware and calculative of the woman's ovulation period and all that. That could be another option of knowing when it would be safe to have sex without bothering about conception.
That isnt reliable at all. Women homones changes time to time.. No woman will accept this most expecially if u dont want any more kids