A randomized, double-blind study of iodine supplementation during pregnancy in Sweden: pilot evaluation of maternal iodine status and thyroid function
Open Access
- 23 February 2021
- journal article
- research article
- Published by Springer Science and Business Media LLC in European Journal of Nutrition
- Vol. 60 (6), 1-12
- https://doi.org/10.1007/s00394-021-02515-1
Abstract
Purpose Pregnant women in Sweden are mildly iodine deficient. We investigated the effect of daily iodine supplementation on the iodine and thyroid status of pregnant women. Methods In this pilot, randomized, double-blind trial, 200 thyroid-healthy pregnant women were recruited at mean (standard deviation) pregnancy week 8.85 (1.62) and assigned (1:1) to daily intake of a multivitamin tablet with or without 150 μg of iodine. Urine and serum samples were collected at baseline and once during the second and third trimesters. Urinary iodine concentration (UIC), serum thyroglobulin (Tg), thyroid-stimulating hormone (TSH), free thyroxine (FT4), and thyroid peroxidase antibodies (TPOabs) were analyzed. Neonatal TSH data were collected. UIC and Tg were also analyzed in a group of 89 thyroid-healthy non-pregnant women of reproductive age (WRA). Results At baseline, the intervention and the control groups had similar median UIC (interquartile range (IQR)): 110 μg/L (74–119) and 111 μg/L (66–168), respectively. The intervention group reached iodine sufficiency with median UIC (IQR) 139 μg/L (89–234) and 136 μg/L (91–211) in the second and third trimester, respectively, without significant difference from the lower limit of the recommended range, i.e. 150–250 μg/L (p = 0.42 and p = 0.87, respectively). The intervention group had higher median UIC and lower median Tg compared to the control group during the second (p < 0.001 and p = 0.019, respectively) and third trimester (p < 0.001 and p = 0.003, respectively), whereas thyroid hormones, serum TPOabs, and neonatal TSH were similar. The WRA group presented median UIC (IQR) 65 μg/L (30–98) and median Tg (IQR) 18 μg/L (13–27). Conclusion A daily supplement containing 150 μg of iodine to a group of pregnant women with mild iodine deficiency improved the iodine status from mild ID to iodine sufficiency. This improvement seems to have had a positive impact on maternal thyroglobulin. This study is now under extension to investigate the children’s neuropsychological development. Trial registration ClinicalTrials.gov Identifier NCT02378246, May 3, 2015, retrospectively registered.Keywords
Funding Information
- The ALF agreement (ALFGBG-770691, ALFGBG-717311)
- Healthcare Board, Region Västra Götaland (VGFOUREG-291101, VGFOUREG-366351, VGFOUREG-458361)
- Allmänna BB fonden och Queen Silvias Jubilee Fund
- University of Gothenburg
This publication has 45 references indexed in Scilit:
- Iodine Supplementation throughout Pregnancy Does Not Prevent the Drop in FT4 in the Second and Third Trimesters in Women with Normal Initial Thyroid FunctionEuropean Thyroid Journal, 2013
- The Effects of Iodine Deficiency in Pregnancy and InfancyPaediatric and Perinatal Epidemiology, 2012
- Maternal thyroid function in different conditions of iodine nutrition in pregnant women exposed to mild-moderate iodine deficiency: an observational studyClinical Endocrinology, 2011
- Effect of Iodine Supplementation During Pregnancy on Infant Neurodevelopment at 1 Year of AgeAmerican Journal of Epidemiology, 2011
- Thyroid volume in Swedish school children: a national, stratified, population-based surveyEuropean Journal of Clinical Nutrition, 2010
- Differences in serum thyroglobulin measurements by 3 commercial immunoradiometric assay kits and laboratory standardization using Certified Reference Material 457 (CRM‐457)Head & Neck, 2010
- Adequate iodine nutrition in Sweden: a cross-sectional national study of urinary iodine concentration in school-age childrenEuropean Journal of Clinical Nutrition, 2008
- The Adverse Effects of Mild-to-Moderate Iodine Deficiency during Pregnancy and Childhood: A ReviewThyroid®, 2007
- Composition of Swedish dairy milkInternational Dairy Journal, 2003
- IODINE DEFICIENCY DISORDERS (IDD) AND THEIR ERADICATIONThe Lancet, 1983