Iodine supply in the womb may be linked to the child’s literacy

May 20, 2013

A new study from Australia has shown that children who did not receive enough iodine in the womb performed worse on literacy tests as nine-year-olds than their peers.
The longitudinal study examined standardized literacy test scores of 228 children at the age of nine who were born during a period of mild iodine deficiency in the population (1). The results showed that inadequate iodine exposure during pregnancy was associated with lasting effects: as nine-year-olds, the participants had lower scores on the test, particularly in spelling, compared to children with sufficient iodine supply. Inade-quate iodine exposure was not associated with lower scores on math tests.
The researchers commented that although the participants’ diet was fortified with iodine during childhood, later supplementation was not enough to reverse the impact of the deficiency during pregnancy. Iodine plays a key role in brain development and even mild deficiency during pregnancy can harm the baby’s neurological development. The scientists theorized that iodine deficiency may take more of a toll on the development of auditory pathways and, consequently, auditory working memory; thus there was more of an impact on stu-dents’ spelling ability than their mathematical reasoning ability.

The researchers emphasized that iodine deficiency during pregnancy is preventable: pregnant women should follow public health guidelines and take daily dietary supplements containing iodine. Public health supplemen-tation programs also can play a key role in monitoring how much iodine the population is receiving and acting to ensure at-risk groups receive enough iodine in their diet. In Australia, bread manufacturers began using iodized salt in October 2001 as part of a voluntary iodine fortification program.


  1. Rebagliato M. et al. Iodine Supplementation During Pregnancy and Infant Neuropsychological Development: INMA Mother and Child Cohort Study. American Journal of Epidemiology. Published online April 2013.