ESPE Yearbook of Paediatric Endocrinology

To read the full abstract: J Clin Endocrinol Metab. 2019 Mar 28. pii: jc.2018-02559. [Epub ahead of print]

This meta-analysis aimed to define the effect of mild to moderate iodine deficiency on child neurological outcome. The authors combined data from three large prospective national studies on 6180 mother child pairs with available urinary iodine and creatinine concentrations in pregnancy and child IQ.

Iodine status differed between the three cohorts, from sufficient (Generation R, The Netherlands [1]), to mildly deficient (INMA, Spain [2]) and moderately deficient (ALSPAC, UK [3]). Importantly, to provide robust results, the authors used statistical methods to harmonize laboratory results, and defined a set of possible confounding factors and approaches to avoid selection bias for drop-outs in the three cohorts.

The main result was a significant curvilinear association of urinary iodine/creatinine concentration with verbal but not for non-verbal IQ. However, the overall effect on verbal IQ was dependent on gestational age at measurement of urinary iodine, and ranged from -5 IQ points below 12th gestational week to -3 IQ points between 12th−14th gestational weeks in the offspring. This association was present beyond the 14th gestational week.

This study adds to current knowledge that even mild to moderate iodine deficiency is associated with adverse neurodevelopmental outcome in offspring, if present during the first trimester. In view of these results, future randomized controlled studies should start with screening for iodine deficiency and supplementation ideally before pregnancy.

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2. Kooijman MN, Kruithof CJ, van Duijn CM, Duijts L, Franco OH, van IJzendoorn MH, de Jongste JC, Klaver CC, van der Lugt A, Mackenbach JP, Moll HA, Peeters RP, Raat H, Rings EH, Rivadeneira F, van der Schroeff MP, Steegers EA, Tiemeier H, Uitterlinden AG, Verhulst FC, Wolvius E, Felix JF, Jaddoe VW. The Generation R Study: design and cohort update 2017. Eur J Epidemiol. 2016;31:1243–64. PMID: 28070760.

3. Guxens M, Ballester F, Espada M, Fernández MF, Grimalt JO, Ibarluzea J, Olea N, Rebagliato M, Tardón A, Torrent M, Vioque J, Vrijheid M, Sunyer J; INMA Project. Cohort Profile: the INMA–Infancia y Medio Ambiente–(Environment and Childhood) project. Int J Epidemiol. 2012;41:930–40. PMID: 21471022.

4. Boyd A, Golding J, Macleod J, Lawlor DA, Fraser A, Henderson J, Molloy L, Ness A, Ring S, Davey Smith G. Cohort Profile: the ‘children of the 90s’–the index offspring of the Avon Longitudinal Study of parents and children. Int J Epidemiol. 2013;42:111–27. PMID: 22507743.