It can be. It depends on circumstances.
My parents married later in life; my father was a widower when he met my mother who was unmarried. When they married, my father was 43 and my mother 37 (side note, my father was Anglican, but they married-in 1955-with dispensation and my father agreed the children would be raised Catholic).
Nature followed its course and they had their first child in 1956, a boy. He died of a rare childhood cancer (neuroblastoma) a little over two years later. By then my mother was 40 and my father 46. I would assume they thought they were too old to have another child naturally; 40+, the risks for the mother and child go up; I remember my late mother telling me (when I was an adult) that her doctor advised adoption instead of having another child naturally. So my parents adopted a 6-week old baby, as it turned out, myself, instead of having another child naturally.
These hypothetical threads are just that, hypothetical. Real life, there are numerous different circumstances. We should avoid making rash judgments about people’s choices.
Would it have been preferable for my parents to have another child naturally instead? I think it’s presumptuous to judge their choice. I am certainly grateful I was adopted by them. They gave me a good life and brought me up in the faith. Even my Anglican father would take me to Mass if my mother was ill; I rarely missed Mass as a child because of his dedication to his promise of raising the kids Catholic.
I thin it would be equally presumptuous to judge anyone’s choice. Having (or not) a child is a very personal decision between the couple and God.