Look at Japan, for example. They're going herbivore.

There's always been a correlation between free resources (wealth) and sexlessness.

In the 1960s they did a series of experiments with mouse colonies being given unlimited food.

The colonies grew, then suddenly new generations of mice quit being interested in mating, and the colony completely collapsed.

Not saying it's going to completely collapse on the societal scale, but the obvious correlation between poverty and high birth rates seems to be signal and not noise.

Big families will remain a poor country thing and advanced economies will be populated by increasingly asexual beings.

It looks like the rich countries will continue to import people from foreign countries to replace the generation gap caused.

This will lift the poor nations out of poverty I hope.