A few decades ago, some people who didn't want to kids anyway got a great excuse to not do what they didn't want to do - the Population Bomb, courtesy of doomsday prophets like Paul Ehrlich and John Holdren.
In their book "Ecoscience" (with Anne Ehrlich), they argued that if people did not choose to stop having kids, it was worth considering having government do it for them. They advocated a Planetary Regime, and with it the prospect of forced abortion and sterilization.