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Association of maternal iodine status with child IQ: a meta-analysis of individual-participant data

Levie, Deborah, Korevaar, Tim I M, Bath, Sarah C, Murcia, Mario, Dineva, Mariana, Llop, Sabrina, Espada, Mercedes, van Herwaarden, Antonius E, de Rijke, Yolanda B, Ibarluzea, Jesús M , Sunyer, Jordi, Tiemeier, Henning, Rayman, Margaret P, Guxens, Mònica and Peeters, Robin P (2019) Association of maternal iodine status with child IQ: a meta-analysis of individual-participant data The Journal of Clinical Endocrinology & Metabolism, 104 (12). pp 5957-5967.

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While the consequences of severe iodine deficiency are beyond doubt, the effects of mild-to-moderate iodine deficiency in pregnancy on child neurodevelopment are less well established.


To study the association between maternal iodine status during pregnancy and child IQ and to identify vulnerable time-windows of exposure to suboptimal iodine availability.


Meta-analysis of individual-participant data from three prospective population-based birth cohorts: Generation R (The Netherlands), INMA (Spain), and ALSPAC (United Kingdom); pregnant women were enrolled between 2002-2006, 2003-2008, and 1990-1992, respectively.


General community.


6180 mother-child pairs with measures of urinary iodine and creatinine concentrations in pregnancy and child IQ. Exclusion criteria were multiple pregnancy, fertility treatment, medication affecting the thyroid, and pre-existing thyroid disease.



Main Outcome Measure

Child non-verbal and verbal IQ assessed at 1.5-8 years of age.


There was a positive curvilinear association of the urinary iodine-to-creatinine ratio (UI/Creat) with mean verbal IQ only. UI/Creat ˂ 150 µg/g was not associated with lower non-verbal IQ [-0.6 points, 95% CI -1.7 to 0.4, P=0.246] or lower verbal IQ [-0.6, 95% CI -1.3 to 0.1, P=0.082]. Stratified analyses showed that the association of UI/Creat with verbal IQ was only present up to 14 weeks of gestation.


Fetal brain development is vulnerable to mild-to-moderate iodine deficiency, particularly in the first trimester. Our results show that any potential randomized, controlled trial investigating the effect of iodine supplementation in mild-to-moderate iodine deficient women on child neurodevelopment, should start with supplementation not later than the first trimester.

Item Type: Article
Divisions : Faculty of Health and Medical Sciences > School of Biosciences and Medicine
Authors :
Levie, Deborah
Korevaar, Tim I M
Bath, Sarah
Murcia, Mario
Llop, Sabrina
Espada, Mercedes
van Herwaarden, Antonius E
de Rijke, Yolanda B
Ibarluzea, Jesús M
Sunyer, Jordi
Tiemeier, Henning
Rayman, Margaret
Guxens, Mònica
Peeters, Robin P
Date : December 2019
DOI : 10.1210/jc.2018-02559
Copyright Disclaimer : Copyright © 2019 Endocrine Society
Depositing User : Clive Harris
Date Deposited : 15 Apr 2019 10:06
Last Modified : 29 Mar 2020 02:08

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