The population should be declining. It's a sign of rising living standards AS WELL AS increasing cost of living. There is simply no reason for human society to exist if we're just going to mindlessly procreate and work til death like animals.
Immigration is just kicking the can down the road.
That said, I read a think-tank piece saying that increased pay and cheaper childcare wasn't increasing childbirth rates. But they missed out the biggy IMO. More TIME.
If there were a standard 25-30h working week for EVERYONE, then working age people would be able to keep themselves healthier (exercise and better food), care for their families better (old and young).
It's absolutely ridiculous that we are working the hours we do and expected to outsource everything that just a few decades ago was done by 50% of the population.
Cut working hours. It's that simple.