Capitalists heighten contradictions. They don't solve them. Proletarianization destroys the productive basis for the nuclear family while the capitalist state upholds it as an institution. Only the socialist state can resolve this contradiction with socialized childcare & childrearing, children's autonomy, abolition of marriage, etc. (sorry USSR you didn't go far enough). The capitalist solution is reaction, a return to 19th century working conditions, family relations, and religiosity that saw high birth rates. Unfortunately that all existed within the context of things, so it's probably impossible to recreate at large scale.