Abstract
It is well known that severe iodine deficiency during pregnancy affects fetal brain development and has implications for cognition in later life, including reduced intelligence quotient (IQ) scores.1 However, the effects of mild-to-moderate deficiency during pregnancy are less well known. Findings of observational studies in mildly-to-moderately iodine-deficient pregnant women have shown an association with lower IQ, reading ability,2 and spelling scores in offspring.3 Although several randomised controlled trials of iodine supplementation in pregnancy have been done in regions of mild-to-moderate iodine deficiency, they did not measure neurodevelopment in offspring.