The effect size was an increase of 0.83, 0.82 and 0.32 SD IQ points respectively, for the children living in IS communities compared with those living in iodine deficient areas with no iodine supplementation, with inadequate iodine supplementation, or children who had received iodine during their mothers’ pregnancy and after birth
(equal to 12.45, 12.3, 4.8 IQ points, respectively).