If there is insufficient supply, housing prices go up.
[1] https://www.aljazeera.com/economy/2023/7/14/japans-abandoned...
[2] https://www.ey.com/en_us/strategy/declining-enrollment-in-pu...
That could increase demand even if the population decreased slightly (which it didn’t, according to another reply)
This is driving up the demand a lot in central areas.
The houses left behind are not desirable for the same reason so many opt to keep them as summer homes, leading to shortages in the districs as well.
A lot of this has to do with jobs. We've lost a lot of jobs in the districs due to various reasons, and at some point these towns collapse. You need a certain minimum number of folks to have a decent school, a hospital etc. Once population drops too low the hospital gets shut down say and it's downhill from there.
[1]: https://www.nrk.no/vestland/byene-vokser-_-distriktene-blor-...
Are you sure most houses in the Nordics are occupied by the same family most of the time?
Another huge problem right now is that the high prices has made it tricky for _older_ people to move, a large rent controlled apartment for an retired person is far cheaper than even the smallest new apartments if the lease is changed, so you have tons of retired people with kids that moved out (or should have moved out) living in 4-5 bedroom flats whilst families are crammed into smaller ones.
The only way out is to buy an apartment/house instead of renting, but here profit-taxation comes into play making elder people hesitant about selling because the huge price increases (often 90%) makes the 30% profit tax almost 30% of their selling price so they actually can't even afford to buy something reasonable since it'd anything relatively smaller would be too expensive for them.
One way out of this would be to lower the profit-tax of a dwelling by 0.5-1% for each year lived in it, that'd make retired people able to sell their dwellings w/o hardly any taxes and should enable a more dynamic market.
Eg in sweden, deregulation: https://www.thelocal.se/20230627/explained-swedens-plans-to-...
In fact only Lithuania, Latvia and Estonia of the Northern Europe countries are showing a long term decline.
There's other issues though (see my sibling post to GP)
So we really needed to think of this a few years ago. It might still be possible, but now it is an uphill battle and will be a much higher risk pregnancy to boot.
If we had high birth rates without building housing that would also drive up housing prices.
As years go by, life becomes more complicated, not less. With or without children.
Having children also involves sacrifice, improvisation, unpredictability, suffering... and lots of people are apparently allergic to all of those things.
Rightfully so. There is no extra credit for unnecessarily burdening yourself.