Prenatal and concurrent blood mercury concentrations and associations with IQ in canadian preschool children

•Examined associations between prenatal and child blood mercury (Hg) with child IQ.•Cord blood Hg with low fish intake was associated with lower performance IQ in males.•Cord blood Hg with high fish intake was associated with higher IQ in females.•Each doubling of child blood Hg associated with 1-point increase in IQ in females.•Results highlight the beneficial effects of fish intake during pregnancy.