Should iodine supplementation be universally recommended for pregnant women in Brazil? A position statement from the Thyroid Department of the Brazilian Society of Endocrinology and Metabolism (SBEM).

Abstract

Background: A U-shaped relationship exists between maternal urinary iodine concentration (UIC) and the risk of thyroid dysfunction, adverse pregnancy outcomes, and neurological deficits in offspring. Both iodine deficiency and excess should be avoided during pregnancy. The WHO recommends increased iodine intake during pregnancy due to elevated thyroid hormone production and fetal iodine transfer. In countries with universal salt iodization, additional supplementation is generally not advised, although iodization alone may be insufficient. In Brazil, salt iodization has reduced iodine deficiency disorders, but in 2013, regulatory agencies lowered iodine levels in salt due to high population-wide salt intake. Without national surveys, it remains unclear whether current iodine levels in table salt are sufficient for pregnant women.

Materials and methods: The clinical questions addressed in this document were derived from stakeholder feedback and input from panel members. The group synthesized the available knowledge on this topic by conducting electronic database searches, reviewing and selecting relevant citations, and critically appraising selected studies.

Results: The group recommends exclusive use of regulated iodized salt during pregnancy. Iodine supplementation should be individualized for at-risk pregnant women, including those with chronic gastrointestinal disorders, restricted diets, or malabsorption conditions. Excess iodine intake should be avoided. In alignment with public policies under PNAISAL, health education on appropriate salt use and storage should be reinforced in primary care. Urinary iodine tests should be used for population-level assessment only.

Conclusion: These recommendations aim to support clinical decision-making regarding iodine supplementation during pregnancy in Brazil, thereby improving maternal and fetal health outcomes.