It looks like a reduced birth rate is already a fairly natural consequence of higher standards of living.
People chose not to have children for economic reasons, exactly like in the poorer countries people chose to have lots for economic reasons.
As mentioned in other posts, population reduction by birth number reduction will lead to further skewing of the age, which is just bareable for sociery if the reasoning for not having children was sound, but isn't if the reduction is artificially induced.
Reductionist and proud of it.
Being ignorant is not so much a shame, as being unwilling to learn. Benjamin Franklin
Chase after the truth like all hell and you'll free yourself, even though you never touch its coat tails. Clarence Darrow
A person who won't read has no advantage over one who can't read. Mark Twain