You're not getting it. In the UK, currently people are finding it difficult heating their homes and you're talking about people living below their living standards.
You make a good point btw.
As you can see the part where the U.K. birth rate rose (only time since 1960s) was in the New Labour government. Rose to 1.9+ (close to replacement level) and now back down to 1.5
This shows as families get poorer women are forced to work more and can’t afford children. Labour was always known to give many benefits to families. Now the Conservatives have brought in 2 child limit for benefits.
I think back in the 2000s my mum got nearly £20k in benefits from 5 children. Which was a lot back then.
But you must accept this is unlikely to happen again. 2000s is the most prosperous decade ever. The world will get poorer and resources will be more scarce because of climate change.
So the truth is the best way to increase births is reduce women participation in work and allow men to raise a family on one income. So then the housewife can raise children, aren’t distracted by work, make as many babies as possible.