Iodine deficiency during pregnancy affects a child’s neurodevelopment. Much is known about severe deficiency, but little so far about mild to moderate cases. A recent study published in The Journal of Nutrition examined the association between iodine intake of pregnant mothers with and without supplements and their child’s cognitive development. The data shows that mild to moderate iodine deficiency does correlate with reduced cognitive development, though the use of supplements does not counteract these effects.


Iodine deficiency is one of the most common nutrient deficiencies in the world today. A severe iodine deficiency during pregnancy strongly affects a child’s neurodevelopment. Crucial to the production of thyroid hormones in the mother and fetus, iodine is thus essential for brain development in the fetus and child. Iodine deficiency is one of the main causes of preventable brain damage worldwide.Intelligence is also correlated with iodine, the introduction of iodized salt to a population with extremely low iodine intake increases IQ. Though the effects of severe iodine deficiency are well known, mild to moderate deficiency has yet to be fully investigated. As iodine is so crucial during pregnancy, even mild deficiency may affect cognitive development. Currently, the World Health Organization (WHO)recommends iodine supplements in populations at risk of severe iodine deficiency; there is a dearth of information on whether or not supplements should be recommended in populations not at risk, or at risk of mild to moderate iodine deficiency

Due to shifts in diet, the population of Norway is at risk of mild to moderate iodine deficiency, which, though detrimental for Norway, is beneficial for study. The Norwegian Mother and Child Cohort Study, MoBA, is one of the world’s largest pregnancy cohorts and also the largest study yet to include data on iodine intake during pregnancy. An investigation published in The Journal of Nutrition used data from MoBA to explore the associations between a mother’s iodine intake and child’s neurodevelopment as well as the effect of iodine supplements on the child’s neurodevelopment. Nearly, 50,000 mother-child pairs were included in this study. Data was gathered via questionnaires: a general questionnaire around week 17 of pregnancy, a food-frequency questionnaire around week 22 and another questionnaire when the child was 3 years old. The food-frequency questionnaire used was designed to capture dietary habits and the use of supplements during the first half of pregnancy and has been rigorously validated. The outcomes of this study were based on the final questionnaire in which the mothers reported the cognitive development and behaviour problems of their children. These reports, also, are validated and focus on language development, communication skills, motor abilities as well as behaviour problems.

Now, the results: low iodine intake is associated with increased risk of delays in language development, behavioural problems, as well as underdeveloped communication and fine motor skills. The use of iodine supplements was not found to correct the deficiencies associated with low iodine intake. This may be due to the importance of regular iodine intake for leading up to pregnancy; starting iodine supplementation during pregnancy might be too late. Though, this does not portend too darkly. The effects of mild to moderate iodine deficiency are quite small and only noticeable in such a large sample group. Also, most Norwegian infants and toddlers do get adequate amounts of iodine due to their diets including much more dairy than those of adults. These healthy diets should reduce the effects of iodine deficiency during pregnancy.


Written by Brian Jones

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