Actually, it's really striking that even in America -- the developed country with the #1 highest birthrate -- still falls below the replacement rate. What is it that's inversely correlated between growing wealth and having children? Especially since it was likely to opposite for most of human history? (i.e. large families were a sign of wealth and power).
PS - I can't resist offering my own experience as a parent - what a treasure to have discovered that I'm capable of such love, and to get to watch this love transform me into a better person than who I was before. This kind of love demands everything of you, but through it you discover a truer and stronger version of yourself too.