Research appearing in the Journal of Pediatrics ( 2011 Sep;159(3):447-53) looked at the relationship between maternal thyroid function, iodine levels and child development. The level of free thyroxine in the mothers of the children in the study was measured during the first trimester of pregnancy. The 86 children involved in the study were evaluated using the Bayley Scale of Infant Development at 12, 18 and 24 months of age.
Researchers found that there was a relationship between the mothers’ free thyroxine levels and the children’s psychomotor development at ages 18 months and 24 months. The children of mothers in the bottom 25th percentile of free thyroxine levels tended to be more developmentally delayed than the children of mothers with higher thyroxine levels. The authors of the study saw these findings as showing a need for iodine supplementation before conception and during pregnancy and lactation.