I was first alerted to this issue 20 years ago reading a booklet (published Nov 2003) on the fertility crisis by Malcolm Turnbull, who later became Prime Minister of Australia, yet did nothing about the issue when in power.
Re-reading it now, I am struck by how much worse the situation, already bad in 2003, has got. Almost all countries mentioned have had total fertility rates fall substantially, some by over 30%!
Korea from 1.14 to 0.7
Japan from 1.4 to 1.0