Yeah, my understanding in Japan, South Korea, and most countries with "fertility problems" is that they have almost zero correlation with any personal human's "fertility problems": they instead have to do with too many humans simply choosing not to reproduce (and for shockingly many of them, choosing to avoid romantic partnership altogether).

The core of that in turn is that capitalism treats human beings as replaceable and disposable cogs in the "earn me enough money for another yacht" machine and nobody wants to reproduce when treated that way.