Even though intelligence is negatively correlated with fertility rate, it is positively correlated with survival rate of offspring. The net effect is not clear.

Even though intelligence is negatively correlated with fertility rate, it is positively correlated with survival rate of offspring. The net effect is not clear. Apart from that, when you differentiate between men and women, the correlations turn out to be different: while women still have a negative correlation, for men the correlation between IQ and fertility rate turns positive. See for instance https://en.wikipedia.org/wiki/Fertility_and_intelligence https://en.wikipedia.org/wiki/Fertility_and_intelligence