The effect of iodine deficiency during pregnancy on child development

Proc Nutr Soc. 2019 May;78(2):150-160. doi: 10.1017/S0029665118002835. Epub 2019 Jan 15.


It is well known that severe iodine deficiency during pregnancy may cause impaired brain development in the child, with effects on cognitive and motor function, hearing and speech. Whether mild-to-moderate deficiency also affects neurological development is less well known, but in the past decade a number of observational studies have been conducted to answer this question and these studies are reviewed in this article. The picture is now emerging that even mild-to-moderate iodine deficiency during pregnancy may be associated with subtle impairments in cognition and school performance, although the evidence from randomised controlled trials is still lacking. As global efforts to eradicate iodine deficiency in populations continue, it is more likely that mild-to-moderate, rather than severe, iodine deficiency will be the issue of concern in pregnancy, and therefore further research in regions of mild-to-moderate deficiency is required to strengthen the research base and to inform public-health policy.

Keywords: RCT randomised controlled trial; T4 thyroxine; TSH thyroid-stimulating hormone; UIC urinary iodine concentration; fT4 free T4; Child development; Iodine; Pregnancy.

Publication types

  • Review

MeSH terms

  • Brain / growth & development
  • Child
  • Child Development*
  • Cognition
  • Dietary Supplements
  • Female
  • Humans
  • Iodine / administration & dosage
  • Iodine / deficiency*
  • Learning Disabilities
  • Pregnancy
  • Pregnancy Complications / physiopathology*
  • Prenatal Exposure Delayed Effects / physiopathology*
  • Thyroid Gland / embryology
  • Thyroid Hormones / physiology


  • Thyroid Hormones
  • Iodine