Associations between maternal urinary iodine assessment, dietary iodine intakes and neurodevelopmental outcomes in the child: A Systematic Review

Anna M. Monaghan, Maria S Mulhern, Emeir M. McSorley, JJ Strain, Matthew Dyer, van Wijngaarden Edwin, Alison J. Yeates

Research output: Contribution to journalReview articlepeer-review

14 Citations (Scopus)
58 Downloads (Pure)

Abstract

Objective: Mild to moderate iodine deficiency during pregnancy has been associated with adverse neurodevelopmental outcomes in offspring. Few research studies to date combine assessment of urinary iodine (UIC and/or ICr), biomarkers that best reflect dietary intake, with reported dietary intake of iodine rich foods in their assessment of iodine deficiency. Thus, a systematic review was conducted to incorporate both these important measures. Design: Using PRISMA guidelines, a comprehensive search was conducted in three electronic databases (EMBASE®, MedLine® and Web of Science®) from January 1970–March 2021. Quality assessment was undertaken using the Newcastle Ottawa Scale. Eligible studies included reported assessment of iodine status through urinary iodine (UIC and/or ICr) and/or dietary intake measures in pregnancy alongside neurodevelopmental outcomes measured in the children. Data extracted included study author, design, sample size, country, gestational age, child age at testing, cognitive tests, urinary iodine assessment (UIC in μg/L and/or ICr in μg/g), dietary iodine intake assessment and results of associations for the assessed cognitive outcomes. Results: Twelve studies were included with nine reporting women as mild-moderately iodine deficient based on World Health Organization (WHO) cut-offs for urinary iodine measurements < 150 μg/l, as the median UIC value in pregnant women. Only four of the nine studies reported a negative association with child cognitive outcomes based on deficient urinary iodine measurements. Five studies reported urinary iodine measurements and dietary intakes with four of these studies reporting a negative association of lower urinary iodine measurements and dietary iodine intakes with adverse offspring neurodevelopment. Milk was identified as the main dietary source of iodine in these studies. Conclusion: The majority of studies classified pregnant women to be mild-moderately iodine deficient based on urinary iodine assessment (UIC and/or ICr) and/or dietary intakes, with subsequent offspring neurodevelopment implications identified. Although a considerable number of studies did not report an adverse association with neurodevelopmental outcomes, these findings are still supportive of ensuring adequate dietary iodine intakes and urinary iodine monitoring throughout pregnancy due to the important role iodine plays within foetal neurodevelopment. This review suggests that dietary intake data may indicate a stronger association with cognitive outcomes than urinary iodine measurements alone. The strength of this review distinguishes results based on cognitive outcome per urinary iodine assessment strategy (UIC and/or ICr) with dietary data. Future work is needed respecting the usefulness of urinary iodine assessment (UIC and/or ICr) as an indicator of deficiency whilst also taking account of dietary intakes.

Original languageEnglish
Number of pages13
JournalThyroid Research
Volume14
Issue number1
Early online date7 Jun 2021
DOIs
Publication statusPublished online - 7 Jun 2021

Bibliographical note

Funding Information:
Funding has been provided as part of the Seychelles Child Development Study, Nutrition Cohort 2 grant (National Institute of Health (NIH R01-ES010219) which has supported the PhD studies of the 1st author (Anna Monaghan).

Funding Information:
With thanks to Ms. Joan Atkinson from Ulster University library services for her help with the initial systematic review search process.

Publisher Copyright:
© 2021, The Author(s).

Keywords

  • pregnancy
  • neurodevelopment
  • iodine
  • urinary iodine assessment
  • dietary iodine intakes
  • Offspring
  • Pregnancy
  • Neurodevelopment
  • Dietary iodine intakes
  • Urinary iodine assessment

Fingerprint

Dive into the research topics of 'Associations between maternal urinary iodine assessment, dietary iodine intakes and neurodevelopmental outcomes in the child: A Systematic Review'. Together they form a unique fingerprint.

Cite this