Reduced educational outcomes persist into adolescence following mild iodine deficiency in utero, despite adequacy in childhood: 15-year follow-up of the gestational iodine cohort investigating auditory processing speed and working memory

There is increasing evidence that even mild gestational iodine deficiency (GID) results inadverse neurocognitive impacts on offspring. It’s unclear, however, if these persist long-term andwhether they can be ameliorated by iodine sufficiency in childhood. We followed a unique cohort(Gestational Iodine Cohort, n = 266) where gestation occurred during a period of mild populationiodine deficiency, with children subsequently growing-up in an iodine replete environment.We investigated whether associations between mild GID and reductions in literacy outcomes,observed at age 9-years, persisted into adolescence. Comparisons were made between offspringof mothers with gestational urinary iodine concentrations (UICs) 150 g/L and p = 0.001)) to Year 9 (5.6%, -31.6 (-57.0 to -6.2, p = 0.015)) compared to children whose mothers hadUICs 150 g/L. Associations remained after adjustment for biological factors, socioeconomic statusand adolescent UIC. Results support the hypothesis that mild GID may impact working memory andauditory processing speed. The findings have important public health implications for managementof iodine nutrition in pregnancy