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Iodine Deficiency in Pregnancy Affects Mental Development

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May 22 (Bloomberg) -- Deficiency in iodine, which can be consumed through dairy products and seafood, during pregnancy may have an adverse effect on children’s mental development, according to a study published in the Lancet medical journal.

Following World Health Organization guidelines, women who had iodine levels of less than 150 micrograms per gram of creatinine were classified as being iodine deficient. Children of such women were more likely to have scores in the lowest quartile for verbal ability, reading accuracy and reading comprehension than those whose mothers had sufficient iodine levels, according to the study published today.

The research analyzed urine samples of 1,040 women in the U.K. in their first trimester and their children’s intelligence quotient at age 8 and reading ability at 9. While harmful effects from severe iodine deficiency on brain development is widely recognized, very few studies have studied the mother-to-child link, Alex Stagnaro-Green of George Washington University in Washington DC and Elizabeth Pearce of Boston University said in a comment accompanying the article.

The study “should be regarded as a call to action to public health policy makers,” Stagnaro-Green and Pearce said. “Until measures are taken to ensure that iodine needs can be met by usual dietary sources, pregnant and breastfeeding women should insist that the prenatal vitamins they are prescribed contain iodine.”

A limitation of the study is the authors’ use of one urine sample to measure the mother’s iodine concentration, when 10 samples are usually needed to achieve 20 percent precision, Stagnaro-Green and Pearce said.

To compensate for this, the researchers also measured concentration of creatinine, which gives an indication of how dilute the urine sample is, and presented as a ratio with the iodine reading, they said.

The study was self-funded by its lead researcher Margaret P. Rayman, a professor of nutritional medicine at the University of Surrey, England.

To contact the reporter on this story: Makiko Kitamura in London at

To contact the editor responsible for this story: Phil Serafino at

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