In what sense? My wife and I certainly planned our first child very young (for the US at least; internationally, we were on the late end, like most Americans)
I suspect the increasingly shrinking demographic of churchgoers is different in this regard from the rest of the population. I think they're right in saying people who plan typically don't plan children for before 30, I don't know anyone near my age (early 20s) who is doing that; many don't want children at all.