Referring to women as a having a shelf-life is sexist. Perhaps it was your choice of words. Not all women want to have or, can have, children. And men don't always make good fathers, no matter what their age.
Why wouldn't a woman want to have children? God said to man and woman 'be fruitful and multiply'. I'm most certain we'll have to agree to disagree on those points since I'm taking a decidedly traditional Roman Catholic stance.
How?