anytime they want
well a woman can have 12 periods a year so count that with how many years an average woman lives
a 56 year old women should only "make love" a couple times a year. that's nasty!
her birthday
Body weight times 10 in calories in order to maintain current weight.
positive 3,571 times in a year
2 times a year
52 times a year
1,825 times a year.
Although a forty year old woman is less fertile on the average than a thirty year old woman, it is still possible for a forty year old woman (or even a 45 year old woman) to have a child, and many forty year old women have done so.
I don't believe it works on that basis. It just assumes that a woman will be fertile approximately 13 times a year and that you will have sex during this time.
4 times a year.