title: Mild iodine deficiency during pregnancy is associated with reduced educational outcomes in the offspring: 9-year follow-up of the gestational iodine cohort.
abstract: BACKGROUND
  Severe iodine deficiency (ID) during gestation is associated with neurocognitive sequelae. The long-term impact of mild ID, however, has not been well characterized.
  
  
  OBJECTIVE
  The purpose of this study was to determine whether children born to mothers with urinary iodine concentrations (UICs) <150 μg/L during pregnancy have poorer educational outcomes in primary school than peers whose mothers did not have gestational ID (UIC ≥150 μg/L).
  
  
  METHODS
  This was a longitudinal follow-up (at 9 years old) of the Gestational Iodine Cohort. Pregnancy occurred during a period of mild ID in the population, with the children subsequently growing up in an iodine-replete environment.
  
  
  METHODS
  Participants were children whose mothers attended The Royal Hobart Hospital (Tasmania) antenatal clinics between 1999 and 2001.
  
  
  METHODS
  Australian national curriculum and Tasmanian state curriculum educational assessment data for children in year 3 were analyzed.
  
  
  RESULTS
  Children whose mothers had UIC <150 μg/L had reductions of 10.0% in spelling (-41.1 points, 95% confidence interval [CI], -68.0 to -14.3, P = .003), 7.6% in grammar (-30.9 points, 95% CI, -60.2 to -1.7, P = .038), and 5.7% in English-literacy (-0.33 points, 95% CI, -0.63 to -0.03, P = .034) performance compared with children whose mothers' UICs were ≥150 μg/L. These associations remained significant after adjustment for a range of biological factors (maternal age at birth of child, gestational length at time of birth, gestational age at time of urinary iodine collection, birth weight, and sex). Differences in spelling remained significant after further adjustment for socioeconomic factors (maternal occupation and education).
  
  
  CONCLUSIONS
  This study provides preliminary evidence that even mild iodine deficiency during pregnancy can have long-term adverse impacts on fetal neurocognition that are not ameliorated by iodine sufficiency during childhood.
authors: Menzies Research Institute Tasmania, University of Tasmania, Sandy Bay, Tasmania 7005, Australia. k.l.hynes@utas.edu.au
authors: Kristen L
authors: KL
authors: Hynes
authors: Petr
authors: P
authors: Otahal
authors: Ian
authors: I
authors: Hay
authors: John R
authors: JR
authors: Burgess
mesh_terms: D002648:Child; D003072:Cognition Disorders / Q000209:etiology*; D015331:Cohort Studies; D004521:Educational Measurement; D005260:Female; D005500:Follow-Up Studies; D005527:Food, Fortified; D006293:Health Promotion; D006801:Humans; D007455:Iodine / Q000008:administration & dosage / Q000172:deficiency* / Q000652:urine; D007803:Language Arts; D007859:Learning Disabilities / Q000209:etiology*; D008137:Longitudinal Studies; D008297:Male; D039382:Maternal Nutritional Physiological Phenomena; D018673:Nutrition Policy; D011247:Pregnancy; D011248:Pregnancy Complications / Q000503:physiopathology*; D012720:Severity of Illness Index; D013648:Tasmania
chemical_list: D007455:Iodine