Fertility is negatively correlated to IQ: https://www.sciencedirect.com/science/article/pii/S0160289607000244 https://www.sciencedirect.com/science/article/pii

Fertility is negatively correlated to IQ: https://www.sciencedirect.com/science/article/pii/S0160289607000244 https://www.sciencedirect.com/science/article/pii/S016028960... "There were strong negative correlations found between national IQ and three national indicators of fertility."