That wouldn't capture the main driver of population decline for most these countries.
Seems like the primary cause in most cases is /not/ the fact that deaths are outpacing births but, instead, that emigration is outpacing immigration.
Most of these countries are low-income nations in the EU whose workforce is now leaving to flock to higher-income countries.
We're basically seeing a brain drain in EU countries that need that workforce most to drive future growth. One of the unintended consequences of EU membership.
It's 100% true that the child and working-age population shrinks long before the absolute population starts to dip, and in many ways that's more meaningful.
In fact, shrinking population is further deferred by improving health and longevity.
This means that many countries which seemingly stable population are in fact growing older and older, leading to an eventual cliff.
Also, title should be changed. This is "Population decline projections for 2050".
> The world itself has reached, or is approaching, "peak baby" - though this will be a long plateau.
How did you arrive at the strange idea that we are approaching "peak baby"? Barring some cataclysm, the only plausible mechanism to reach "peak baby" is hitting permanent Malthusian limits.
A more leading indicator is "Countries who have reached peak births".
The world itself has reached, or is approaching, "peak baby" - though this will be a long plateau.