Iodine Supplementation in Pregnancy

Current Recommendations

• The World Health Organization recommends iodine supplementation in pregnancy and lactation only in countries where iodized salt is available in less than 20% of households 1
• The American Thyroid Association, the Endocrine Society, and the US National Academy of Sciences propose that all prenatal supplements should include 150 μg of potassium iodide 2, 3
• Different organizations have varying recommendations for daily iodine intake during pregnancy:
  • WHO/FAO: 250 μg/day 4
  • European Food Safety Authority: 200 μg/day 4
  • US Institute of Medicine: 220 μg/day 4
  • UK Department of Health: 140 μg/day (with no specific increment for pregnancy) 4

Evidence on Benefits and Risks

• A recent Cochrane review highlighted inconclusive evidence regarding iodine supplementation in preconception, pregnancy, and lactation 1, 5
• Potential benefits of supplementation include:
  • Lower likelihood of insufficient iodine status in pregnancy 1
  • Reduced risk of congenital abnormalities 1
  • Decreased incidence of postpartum hyperthyroidism 1
  • Prevention of neonatal goiter and insufficient iodine intake 1
• Potential risks of supplementation include:
  • Overactive thyroid function 1
  • Increased nausea and vomiting during pregnancy 1
  • Elevated thyroid-stimulating hormone levels exceeding the upper limit for gestation 1
  • Risk of maternal hyperthyrotrophinemia in mild iodine deficiency areas 1

Impact on Neurodevelopment

• Studies on neurodevelopmental outcomes show mixed results:
  • In India and Thailand, iodine supplementation during pregnancy did not lead to measurable differences in verbal IQ, performance IQ, or executive function in children at 5.4 years 1, 6
  • A Spanish study found that children whose mothers took ≥150 μg/day from supplements had lower psychomotor development scores compared to those whose mothers consumed <100 μg/day 3, 6
  • Some studies in areas with severe iodine deficiency have shown positive impacts on neurodevelopment 6

Practical Approach to Iodine Supplementation

• Assess regional iodine sufficiency status and local salt iodization programs 1, 4
• Consider supplementation with potassium iodide (150 μg daily) in areas with known iodine deficiency 2, 1
• Ideally, begin supplementation before conception rather than during pregnancy to maximize benefits 1
• Monitor for signs of thyroid dysfunction if supplementation is initiated 1
• Be cautious with supplementation in areas with adequate iodine intake to avoid potential thyroid dysfunction 1