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J Clin Endocrinol Metab. 2019 Mar 28. pii: jc.2018-02559. doi: 10.1210/jc.2018-02559. [Epub ahead of print]

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

Author information

1
The Generation R Study Group, Erasmus University Medical Centre, Rotterdam, The Netherlands.
2
Department of Internal Medicine, Academic Center For Thyroid Diseases, Erasmus University Medical Centre, Rotterdam, The Netherlands.
3
Department of Child and Adolescent Psychiatry/Psychology, Erasmus University Medical Centre-Sophia Children's Hospital, Rotterdam, The Netherlands.
4
ISGlobal, Carrer Doctor Aiguader 88, Barcelona, Spain.
5
Pompeu Fabra University, Barcelona, Carrer Doctor Aiguader 88, Barcelona, Spain.
6
Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Instituto de Salud Carlos III, Madrid, Spain.
7
Department of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.
8
Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Valencia, Spain.
9
Clinical Chemistry Unit, Public Health Laboratory of Bilbao, Basque Government, Parque Tecnológico de Bizkaia, Derio, Spain.
10
Department of Laboratory Medicine, Radboud University Nijmegen Medical Centre, Nijmegen.
11
Department of Clinical Chemistry, Erasmus MC, University Medical Centre, Rotterdam, the Netherlands.
12
Departamento de Sanidad Gobierno Vasco, Subdirección de Salud Pública de Guipúzcoa, Donostia - San Sebastián, Spain.
13
BIODONOSTIA Health Research Institute, San Sebastian, Donostia - San Sebastián, Spain.
14
Facultad de Psicología. University of the Basque Country UPV/EHU, Donostia - San Sebastián, Spain.
15
Hospital del Mar Research Institute (IMIM), Carrer Doctor Aiguader 88, Barcelona, Spain.
16
Department of Social and Behavioral Science, Harvard TH Chan School of Public Health, Boston, MA, USA.

Abstract

CONTEXT:

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.

OBJECTIVE:

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.

DESIGN:

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.

SETTING:

General community.

PARTICIPANTS:

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.

INTERVENTION(S):

None.

MAIN OUTCOME MEASURE:

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

RESULTS:

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.

CONCLUSIONS:

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.

PMID:
30920622
DOI:
10.1210/jc.2018-02559

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