I like finding big correlations, but not this time. The cross-national correlation between mean IQ and the total fertility rate for 178 countries is -.72. That's huge. The world gets dumber with each passing day.
"Man is an enigma. This enigma must be solved, and if you spend all your life at it, don't say you have wasted your time; I occupy myself with this enigma because I wish to be a man."