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Not sure what your point is here, as in the UK the average number of children per woman is <2 and lower than that for Europe as a whole. Increases in population are mainly driven by longer life expectancies and immigration.
Most wealthy countries actually have a fertility issue from an economic perspective, as current birth rates are unsustainable given the likely costs in the future to care for older generations.
Somehow we have to discourage people in wealthy countries from deciding to have that third child. Economic disincentives don't work and are regressive, so how else do you propose to achieve it without cultural norms?