I also know women who have had children after forty, and I think there’s absolutely nothing wrong with that. My mother had me in her late thirties, and although no other children ever came, she was open to having more children up until she had finished menopause.
I agree with the poster who said that people who say a woman is too old to have a child are idiots! Such misguided people are unduly influenced by our secular society. I did a little research on this topic myself a while back, and there are actually all kinds of advantages to having children later in life (not that there’s anything wrong with giving birth in your twenties- I don’t want to discourage people who are called to have children earlier).
I myself am in my late thirties now and still single with no children. If I ever marry, that would put me in my forties or later, and I intend to be open to the possibility of having children. I have many single friends my age who feel the same way. It’s a comfort to know that more people are having children later in life and have done so in the past. It’s God way of telling all of us that it’s not too late, and God’s time is the perfect time.