The US is also suffering from a low fertility rate, at 1.79 (population replacement rate is 2.1), which we made up for in the 20th century by lots of immigration.
(This is one of the factors that informs the great replacement myth, as non-whites approach outnumbering whites in the US. A vocal minority sees this as a bad thing, especially since whites tend to vote Republican and Blacks tend to vote Democrat).
I find it odd and fascinating that the ownership class is terrified by the notion of a lowering population -- babies allegedly grow up to be workers after all -- but are not willing to pass policy to support child rearing, and depend entirely on tradwife propaganda and restricting contraception access and abortion access.
It's especially a problem since our economy is based entirely on growth, with lots of young people providing support for elders.
The US is not unique with this problem. South Korea, Japan and Italy (actually the whole EU) also have low rates and are trying to implement changes to improve fertility, and so far to little effect.