Is potassium iodide (KI) recommended as a routine supplement for every pregnant woman?

Potassium Iodide Supplementation in Pregnancy

Potassium iodide supplementation is not universally recommended for every pregnant woman but should be provided in countries where iodized salt is available in less than 20% of households, according to WHO guidelines. 1

Current Recommendations by Major Organizations

• 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 1
• 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
• Different organizations have varying recommendations for daily iodine intake during pregnancy:
  • WHO/FAO: 250 μg/day 1
  • European Food Safety Authority: 200 μg/day 1
  • US Institute of Medicine: 220 μg/day 1
  • UK Department of Health: 140 μg/day (with no specific increment for pregnancy) 1

Evidence on Benefits and Risks

• A recent Cochrane review highlighted inconclusive evidence regarding iodine supplementation in preconception, pregnancy, and lactation 1

• 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
  • 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 1
  • Some studies in areas with severe iodine deficiency have shown positive impacts on neurodevelopment 1

Current Status of Iodine Intake in Pregnant Women

• Studies show that many pregnant women have insufficient iodine intake:
  • In New York City, more than 50% of pregnant women were at risk for iodine deficiency 2
  • Even with supplementation, over 20% of women remained at risk for deficiency 2
  • In Spain, 66% of pregnant women had urinary iodine concentrations below recommended levels (150 μg/L) 3

Supplementation Practices

• Not all prenatal vitamins contain adequate iodine:
  • Only 57.6% of top-selling prenatal multivitamins in the US contained iodine 4
  • The median iodine content was 150 μg per daily serving, but with a wide range (25-290 μg) 4
  • 24% of prenatal multivitamin doses sold did not contain iodine 4

Practical Approach to Iodine Supplementation in Pregnancy

• Assess regional iodine sufficiency status and local salt iodization programs 1
• Consider supplementation with potassium iodide (150 μg daily) in areas with known iodine deficiency 1
• Ideally, begin supplementation before conception rather than during pregnancy to maximize benefits 1, 5
• 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

Common Pitfalls and Caveats

• Assuming all prenatal vitamins contain adequate iodine - many do not 4
• Starting supplementation too late - ideally should begin before conception 1
• Overlooking dietary sources of iodine - healthcare providers should discuss dietary sources with pregnant women 1
• Failing to consider regional variations in iodine sufficiency 1
• Using kelp or other natural sources with variable iodine content instead of potassium iodide 4