I know because they tell me they use birth control. They argue in it’s favor, and even criticize people who have children or “too many children”. I’ve been married 8 years and have 5 children, the subject of birth control, is like the first thing brought up by strangers that come up to us in public places. They volunteer the information.
Also, the sadness of not being able to have children or less than they would have been taken on had God sent them is always brought up.
Walk around with 5 properly dressed, well behaved children and the world sees something unique, today. That's what they will talk about. They know we are Catholic by what they see. "By their deeds you shall know them".
Remember the movie (the book) Cheaper by the Dozen, the original real one about the Gilbreth's? The public's subject of discussion around them, was always about birth. Same thing happens with my family.
I survived 5 children in their teens at the same time...big deal...I don't ever remember telling anyone about my and my husbands bedroom sessions or weather we used BC or not. It never came up even with friends...who do you hang around with for goodness sake..