“ Yes. It means those who reproduce themselves.
It only means the working class today”
This is one of the problems that capitalism, following the introduction of more effective contraception, more and more members of the proletariat are less keen to reproduce themselves.
I don’t think this is due to any reluctance to have children, but rather the economic pressures that the profit motive that impacts on all sections of society.
Wages are likely to be set at the cheapest level which workers are prepared to accept. In previous periods those wages include the price of the generally inevitable cost of raising children. With choice about reproduction, the economic pressures will always favour the cheapest wages, i.e. the wages of workers who are reluctantly do without having children