12:58am Tuesday 26 May 2020

Mild iodine deficiency during pregnancy linked to reduced educational outcomes in offspring

A new Menzies Research Institute Tasmania study has found that children who did not receive enough iodine in the womb performed worse on literacy tests as 9-year-olds than their peers. The study was published online today in The Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM).

Iodine is absorbed from food and plays a key role in brain development. Even mild deficiency during pregnancy can harm the baby’s neurological development.

“Our research found children may continue to experience the effects of insufficient iodine for years after birth,” said the study’s lead author, Menzies’ research fellow Dr Kristen Hynes.

“Although the participants’ diet was fortified with iodine during childhood, later supplementation was not enough to reverse the impact of the deficiency during the mother’s pregnancy.”

The longitudinal study examined standardised test scores of 228 children whose mothers attended The Royal Hobart Hospital’s antenatal clinics between 1999 and 2001. The children were born during a period of mild iodine deficiency in the population. Conditions were reversed when bread manufacturers began using iodised salt in October 2001 as part of a voluntary iodine fortification program.

The study found inadequate iodine exposure during pregnancy was associated with lasting effects. As nine-year-olds, the children who received insufficient iodine in the womb had lower scores on standardised literacy tests particularly in spelling. However, inadequate iodine exposure was not associated with scores on math tests.

Researchers theorise iodine deficiency may take more of a toll on the development of auditory pathways and consequently auditory working memory and so had more of an impact on students’ spelling ability than their mathematical reasoning ability. 

“Fortunately, iodine deficiency during pregnancy and the resulting neurological impact is preventable,” Dr Hynes said.

“Pregnant women should follow public health guidelines and take daily dietary supplements containing iodine.

Public health supplementation 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 the diet.”

Other researchers on the study included Mr Petr Otahal and Professor John Burgess from Menzies and Professor Ian Hay from the UTAS Faculty of Education.

This Gestational Iodine Cohort study was funded by the Royal Hobart Hospital Research Foundation and the University of Tasmania Cross Theme Grant Scheme.

University of Tasmania

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