Introduction:

Iodine is an essential nutrient required for the biosynthesis of thyroid hormones, which plays an essential role in brain development. In Portugal, the Direção-Geral da Saúde issued a guideline standard in 2013 that recommends supplementing iodine to pregnant or lactating women and, ideally, before conception.

Objective:

The purpose of this review is to determine whether iodine supplementation in pregnancy has an impact on the child's neurodevelopment.

Materials and methods:

An evidence-based review of clinical guidelines, systematic reviews, and randomized clinical trials using the National Institute for Health and Care Excellence, Agency for Healthcare Research and Quality, Canadian databases Medical Association Practice Guidelines Infobase, The Cochrane Library, Database of Abstracts of Reviews of Effectiveness, Bandolier, Evidence-Based Medicine Online, and PubMed was carried out.

Results:

Six systematic reviews and meta-analyses were included and two clinical guidelines were included. These guidelines recommend iodine supplementation before conception, during pregnancy, and during lactation. Iodine supplementation during pregnancy in regions of severe iodine deficiency reduces the risk of cretinism and increases the intelligence quotient in childhood. Effects on neurocognitive development in areas with mild to moderate iodine deficiency are inconsistent.

Discussion:

Maternal iodine supplementation has positive effects on neurodevelopment in regions with severe deficiency. However, there are few good-quality studies carried out in regions with mild to moderate deficiency.

Conclusions:

Well-designed randomized controlled trials in pregnant women are needed to clarify the effects of this supplementation.

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