I don't think reproduction of vertebrates has ever been tried in space. Definitely not humans. It simply isn't known how growing up in moon gravity or no gravity at all affects people. They most likely would never be able to visit the Earth, but maybe they can live healthy lives regardless. Or maybe it's impossible and the fetus dies in the womb. It simply isn't known.
Even if you start mining the asteroids any time in the coming decades, it won't be any thing less than a century after that, until you put humans into permanent colonies.
"Now, Billy, you know your bones and brain need at least .85G to develop properly. You can go live with Dad when you turn 16."
"Aw, Mom, why can't we go live on Earth with Dad?"
"Now, Billy, you know your bones and muscles are used to lunar 0.16G, and won't support your body in full 1G. Your heart isn't strong enough for those conditions either."
See also: Belters from The Expanse.
Pulling stuff out of a gravity well is enough work as it is. Mostly you will have people living and working in neighborhoods, in space, just like you have cities and lot of empty unused land between them on earth.
Like space cities. Then cluster of space cities, then may be a region full of such clusters etc.