I do believe that a lot of people settle down, married or not, and have children, because of family and peer pressure, and they don't really think about the consequences of what they are doing.
The drip-drip-drip of "Well, it's time you had a ring on your finger … Time you made an honest woman of her …" is then followed by the "When are you making us grandparents then … Where's the pitter-patter of tiny feet …" and people go along because they think they should, rather than because they have considered the commitment that parenthood means.
The downside of that cultural attitude, is people being seen as odd or 'unfulfilled' if they make a choice not to have children.
It is wrong, and were I childless from choice, I would give both barrels to anyone I thought was looking down on me, or pitying me for my personal life choices.