My 16 year old Spanish foreign exchange student knows nobody in Spain who intends to marry and have babies.
NONE.
The countries of Japan and South Korea are even worse off.
Plus Japan does not allow immigration.
China is also having a population crisis. All due to the one child policy. They have millions of young men that will never have a wife. There are literally not enough young women to marry. Recently they admitted their population dropped from 1.5 to 1.4 Billion. Keep in mind that .1 difference is 100 million people.
Italy is one of the worst in Europe. Which is why they are still selling houses for under $50K. Some are for sale for a Euro in small villages. All the young people in Italy want to live in the cities. All the opportunities are the northern half of the country.
What all of us first world countries have in common is that people from third world countries actually WANT to come here. They want to escape China and other places.
FYI, I had my roof replaced last week at my house here in NH. The entire crew of eight showed up in a van with MA plates. They were all from Ecuador. Six young men. Two women. Plus a white male foreman from MA. The roofers all looked like they were descendants of the Incas. None were much over 5’ tall. I witnessed one of the young women under 5’ tall pick up a bundle of shingles and climb up a ladder like nothing.