I married when I was forty. It was amazing at that age how many people asked me if we were going to have children. 'No,' I'd say, 'We're not having children.' What is amazing to me now is that I thought I was lying. Keeping a secret. Of course we would have children. Forty is still young.
Why is the word 'childless' unacceptable? It screeches of loss or tragedy, even sterility. At best it's offensive to those who have chosen not to have children, and at worst it's grotesquely insensitive to those permitted no choice.
After divorcing in my late twenties, I was glad I didn't have children. For a time I believed I didn't want kids at all. But in my mid-thirties when my younger sister got pregnant, I absolutely struggled with the choice.