Things that might be true but aren't obviously so

One of the reasons we structure science the way that we do is that there are many things that seem to make logical sense. Theories that can be floated, ideas that seem to run along entirely sensible lines. But it’s not always true that sensible and true are quite the same. So, we need to test the theories against reality. Much of science - when done properly - is in constructing the experiments to try to disprove the idea being floated. Also, the mark of good science is that when reality differs then it’s reality that wins.

Childcare and fertility rates is one of those things:

Affordable childcare is one way to boost Britain’s birth rate

Well, could be, yes. We can all see the logical connection there. If having a child becomes less costly to those having the child - the expenses don’t go away here, of course, they’re just rather more charged across the society though the tax burden - then we might well assume that more children will be had. Given the abortion numbers we can observe that the higher fertility rate is there in potentio, it’s an active choice being made for the children not to arrive. So, yes, could be childcare, could well be.

Except there’s no actual evidence that this is so. Society 50 and 70 years ago had less of that affordable childcare than it does now. The birthrate is lower now than it was then. Looking across European countries we don’t seem to see any correlation between childcare provision in the here and now and the fertility rate.

It’s not even true that the wider issues of maternity leave, maternity pay, the gender pay gap and so on correlate with fertility rates. Among the rich countries Sweden and the US can be considered as being at the opposite ends of the policy spectrum concerning those issues and yet their fertility rates are statistically virtually indistinguishable. And no, immigration (first generation immigrants tend to bring with them their home country fertility rates) isn’t the answer as Sweden has a similar to the US rate for that too (both countries about 14% foreign born).

Childcare costs limiting fertility just seems to be one of those theories that doesn’t have any actual evidence to support it - however sensible the logical process itself.