Relationship between mild iodine deficiency in pregnant women and thyroid function: A meta-analysis

Siyuan Wan; Baiming Jin; Bingxuan Ren; Michael Boah; Hongmei Shen

doi:10.1016/j.jtemb.2023.127197

Relationship between mild iodine deficiency in pregnant women and thyroid function: A meta-analysis

J Trace Elem Med Biol. 2023 Jul:78:127197. doi: 10.1016/j.jtemb.2023.127197. Epub 2023 May 6.

Authors

Siyuan Wan¹, Baiming Jin², Bingxuan Ren³, Michael Boah⁴, Hongmei Shen⁵

Affiliations

¹ Department of Preventive Medicine, Qiqihar Medical University, Qiqihar, Heilongjiang, China. Electronic address: wansiyuan0424@qmu.edu.cn.
² Department of Preventive Medicine, Qiqihar Medical University, Qiqihar, Heilongjiang, China.
³ Centre for Endemic Disease Control, Chinese Centre for Disease Control and Prevention, Harbin Medical University, Harbin, Heilongjiang, China.
⁴ Department of Epidemiology, Biostatistics and Disease Control, School of Public Health, University for Development Studies, Tamale, Ghana.
⁵ Centre for Endemic Disease Control, Chinese Centre for Disease Control and Prevention, Harbin Medical University, Harbin, Heilongjiang, China. Electronic address: shenhm119@hrbmu.edu.cn.

PMID: 37209527
DOI: 10.1016/j.jtemb.2023.127197

Abstract

Background: Pregnant women are among the key groups in iodine nutrition evaluation. The purpose of the present study was to summarize the evidence supporting the relationship between mild iodine deficiency (UIC: 100-150 μg/L) in pregnant women and levels of thyroid function tests.

Methods: This review follows the guidelines for systematic reviews (PRISMA 2020). Three electronic databases (PubMed, Medline, and Embase) were searched for relevant publications in English on the association between mild iodine deficiency in pregnant women and thyroid function. Articles published in Chinese were searched in China's electronic databases (CNKI, WanFang, CBM, and WeiPu). Pooled effects were presented as standardized mean differences (SMDs) and odds ratios (ORs) with 95% confidence intervals (CIs) using fixed or random effect models, respectively. This meta-analysis was registered at www.crd.york.ac.uk/prospero as CRD42019128120.

Results: We summarized the results from 7 articles with 8261 participants. The overall pooled results showed that the levels of FT₃, FT4, and abnormal TgAb (the antibody levels exceeded the upper limit of the reference range) were significantly increased in pregnant women with mild iodine deficiency compared to pregnant women with adequate iodine status (FT₃: SMD=0.854, 95% CI: 0.188, 1.520; FT₄: SMD=0.550, 95% CI: 0.050, 1.051; TgAb: OR=1.292, 95% CI: 1.095; 1.524). Subgroup analysis was carried out on the sample size, ethnicity, country, and gestation of FT₃, FT_4, and TSH, but no plausible factor was found. Egger's tests indicated no publication bias.The increase in FT₃ and FT_4, as well as TgAb levels, in pregnant women is associated with mild iodine deficiency.

Conclusion: Mild iodine deficiency is associated with an increase in FT_3，FT₄ and TgAb levels in pregnant women. Mild iodine deficiency may increase the risk of thyroid dysfunction in pregnant women.

Keywords: Iodine; Meta-analysis; Mild iodine deficiency; Pregnant women; Thyroid function.

Publication types

Meta-Analysis
Review

MeSH terms

Female
Humans
Iodine*
Malnutrition*
Pregnancy
Pregnant Women
Thyroid Function Tests
Thyroid Gland
Thyroid Hormones
Thyrotropin
Thyroxine

Substances

Thyroid Hormones
Iodine
Thyrotropin
Thyroxine