title: Maternal urinary iodine concentration in pregnancy and children's cognition: results from a population-based birth cohort in an iodine-sufficient area.
abstract: OBJECTIVE
  Reports from populations with an insufficient iodine intake suggest that children of mothers with mild iodine deficiency during pregnancy are at risk for cognitive impairments. However, it is unknown whether, even in iodine-sufficient areas, low levels of iodine intake occur that influence cognitive development in the offspring. This study investigated the association between maternal low urinary iodine concentration (UIC) in pregnancy and children's cognition in a population-based sample from a country with an optimal iodine status (the Netherlands).
  
  
  METHODS
  In 1525 mother-child pairs in a Dutch multiethnic birth cohort, we investigated the relation between maternal UIC<150 μg/g creatinine, assessed <18 weeks gestation and children's cognition.
  
  
  METHODS
  Non-verbal IQ and language comprehension were assessed during a visit to the research centre using Dutch test batteries when the children were 6 years.
  
  
  RESULTS
  In total, 188 (12.3%) pregnant women had UIC<150 μg/g creatinine, with a median UIC equal to 119.3 μg/g creatinine. The median UIC in the group with UIC>150 μg/g creatinine was 322.9 μg/g and in the whole sample 296.5 μg/g creatinine. There was a univariate association between maternal low UIC and children's suboptimum non-verbal IQ (unadjusted OR=1.44, 95% CI 1.02 to 2.02). However, after adjustment for confounders, maternal low UIC was not associated with children's non-verbal IQ (adjusted OR=1.33, 95% CI 0.92 to 1.93). There was no relation between maternal UIC in early pregnancy and children's language comprehension at 6 years.
  
  
  CONCLUSIONS
  The lack of a clear association between maternal low UIC and children's cognition probably reflects that low levels of iodine were not frequent and severe enough to affect neurodevelopment. This may result from the Dutch iodine fortification policy, which allows iodised salt to be added to almost all processed food and emphasises the monitoring of iodine intake in the population.
authors.affiliation: Department of Child and Adolescent Psychiatry, Erasmus Medical Centre - Sophia Children's Hospita, Rotterdam, The Netherlands The Generation R Study Group, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors.forename: Akhgar
authors.initials: A
authors.lastname: Ghassabian
authors.affiliation: Department of Child and Adolescent Psychiatry, Erasmus Medical Centre - Sophia Children's Hospita, Rotterdam, The Netherlands The Generation R Study Group, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors.forename: Jolien
authors.initials: J
authors.lastname: Steenweg-de Graaff
authors.affiliation: Department of Internal Medicine, Erasmus Medical Centre, Rotterdam, The Netherlands Rotterdam Thyroid Centre, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors.forename: Robin P
authors.initials: RP
authors.lastname: Peeters
authors.affiliation: Department of Laboratory Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: H Alec
authors.initials: HA
authors.lastname: Ross
authors.affiliation: The Generation R Study Group, Erasmus Medical Centre, Rotterdam, The Netherlands Department of Paediatrics, Erasmus Medical Centre - Sophia Children's Hospital, The Netherlands Department of Epidemiology, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors.forename: Vincent W
authors.initials: VW
authors.lastname: Jaddoe
authors.affiliation: Department of Epidemiology, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.affiliation: Department of Child and Adolescent Psychiatry, Erasmus Medical Centre - Sophia Children's Hospita, Rotterdam, The Netherlands.
authors.forename: Frank C
authors.initials: FC
authors.lastname: Verhulst
authors.affiliation: Department of Child and Adolescent Psychiatry, Erasmus Medical Centre - Sophia Children's Hospita, Rotterdam, The Netherlands Department of Radiology, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors.forename: Tonya
authors.initials: T
authors.lastname: White
authors.affiliation: Department of Child and Adolescent Psychiatry, Erasmus Medical Centre - Sophia Children's Hospita, Rotterdam, The Netherlands Department of Epidemiology, Erasmus Medical Centre, Rotterdam, The Netherlands Department of Psychiatry, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors.forename: Henning
authors.initials: H
authors.lastname: Tiemeier
mesh_terms: D000328:Adult; D002648:Child; D003071:Cognition; D003072:Cognition Disorders / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007455:Iodine / Q000172:deficiency / Q000652:urine*; D008297:Male; D009426:Netherlands; D011247:Pregnancy / Q000652:urine*; D011248:Pregnancy Complications / Q000652:urine; D011446:Prospective Studies
chemical_list: D007455:Iodine
keywords: EPIDEMIOLOGY