Most people associate pronatalism with religionism. Either because of its ‘go forth and multiply’ view, its ‘sanctity of life’ view, or its ‘we have to outnumber them’ view. I agree there’s a relationship, even a causal one. But it’s not that religion ’causes’ pronatalism; rather, some other thing causes both religionism and pronatalism.
What is this other thing? An inability to find fulfilment in the here and now. The sci-fi stories featuring a ‘last’ generation always seem to show some sort of widespread malaise, even despair. What, no kids? Many, not content to die in a few years, decide to kill themselves immediately. If I didn’t know better, I’d call it an existential crisis. One not handled very well. (‘I’m too unimaginative or too lazy, or both, to have made my life worthwhile. I know! I’ll have kids—they’ll make my life worthwhile!) (And then in a really clever leap of logic, they even blame the kids for their existential black hole—’How can I be out following some dream when I gotta put food on the table for you kids?’)
The same people insist on believing there’s a heaven no matter how many photographs of ‘up there’ they’re shown. (Never mind the extensive non-visual physical evidence against the possibility.)
In short, those of us who have purpose and value in our own lives have no need of kids—or heaven. Those of us who don’t, pass the buck.