Mild Iodine Deficit is Bad While Pregnant

Iodine deficiency during pregnancy can have harmful effects on brain development in children

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) Iodine deficiency is “the single most important preventable cause of brain damage” according to the WHO. Contrary to popular belief, kids born in developed nations are at risk too. 

Iodine, primarily found in dairy products and seafood, is essential for normal thyroid function. This nutrient is important for healthy brain development in children.

The damaging effects of severe iodine deficiency on kids of pregnant moms have been well-studied.

But not much is known about the effects of mild to moderate iodine deficiency on cognitive development.

"Ask your obstetrician about iodine supplements."

The study was conducted by Sarah C. Bath, PhD from the Department of Nutritional  Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK along with collaborators from the University of Surrey and the University of Bristol, UK.

The Avon Longitudinal Study of Parents and Children (ALSPAC) is a long-term project with 14,000 women recruited during their pregnancy in the years 1991 and 1992. Since then, the families have been followed to examine the health status and development of the children born to the mothers.

According to a new study, pregnant moms in developed countries are likely to suffer from mild to moderate iodine deficiency much like their counterparts in less developed nations. Results of the study show that even low levels of iodine deficiency during pregnancy can have detrimental effects on brain development in kids.

The researchers looked at the concentration of iodine in urine samples collected in the first trimester of pregnancy from 1040 women.

Since different volumes of urine were collected from the participants, the researchers also calculated the concentration of a substance called creatinine in the urine to check how dilute the sample was.  

Iodine concentrations were stated as the ratio of iodine to creatinine, expressed in micrograms of Iodine per gram of creatinine (μg/g).

According to World Health Organization (WHO) guidelines for normal levels of iodine, women with iodine-to-creatinine ratio of less than 150 μg/g were classified as iodine deficient and the others with ratios equal to or greater than 150 μg/g as iodine sufficient.

One important finding was that more than 65 percent of the participants fell into the iodine deficient category.

The researchers also assessed the mental development of children born to the participants by measuring the kids’ IQ at age 8, and reading ability at age 9.

The study found that kids born to women who were iodine-deficient were 1.5 times more likely to have lower scores on tests for verbal IQ, reading accuracy and reading comprehension. There was also a direct relationship between the level of iodine deficiency and the poor scores. The kids of mothers with levels lower than 50 μg/g performed significantly worse than mothers who had higher levels.  

"Our results clearly show the importance of adequate iodine status during early pregnancy, and emphasize the risk that iodine deficiency can pose to the developing infant, even in a country classified as only mildly iodine deficient," said Professor Margaret P. Rayman, the lead author.

"Pregnant women and those planning a pregnancy should ensure adequate iodine intake; good dietary sources are milk, dairy products and fish. Women who avoid these foods and are seeking alternative iodine sources can consult the iodine fact sheet that we have developed, which is available on the web-sites of the University of Surrey and the British Dietetic Association. Kelp supplements should be avoided as they may have excessive levels of iodine," Dr. Sarah Bath, a co-author and registered dietitian advised.

The authors were funded by a studentship from Wassen International, and the Waterloo Foundation, the Commission of the European Communities,  Quality of Life and Management of Living Resources, and the US National Oceanographic and Atmospheric  Administration.  The ALSPAC study receives funding support from the UK Medical Research Council, the Wellcome Trust and the University of Bristol.

The authors declare no conflicts of interest or financial relationships. 

Reviewed by: 
Review Date: 
May 25, 2013
Last Updated:
August 22, 2013