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

• Published in: Journal of trace elements in medicine and biology Vol. 78; p. 127197
• Main Authors: Wan, Siyuan, Jin, Baiming, Ren, Bingxuan, Boah, Michael, Shen, Hongmei
• Format: Journal Article
• Language: English
• Published: Germany Elsevier GmbH 01.07.2023
• Subjects: Female; Humans; Iodine; Malnutrition; Meta-analysis; Mild iodine deficiency; Pregnancy; Pregnant Women; Thyroid function; Thyroid Function Tests; Thyroid Gland; Thyroid Hormones; Thyrotropin; Thyroxine; FT3; FT4; TSH; CIs; UIC; Mild iodine deficiency; SMDs; Meta-analysis; ORs; TPOAb; TgAb; Pregnant women; Thyroid function; AHRQ; Iodine
• ISSN: 0946-672X; 1878-3252
• DOI: 10.1016/j.jtemb.2023.127197

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. 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. 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, FT4, and TSH, but no plausible factor was found. Egger’s tests indicated no publication bias.The increase in FT3 and FT4, as well as TgAb levels, in pregnant women is associated with mild iodine deficiency. Mild iodine deficiency is associated with an increase in FT3，FT4 and TgAb levels in pregnant women. Mild iodine deficiency may increase the risk of thyroid dysfunction in pregnant women. •This is the first meta-analysis on the relationship between mild iodine deficiency and thyroid function in pregnant women.•Mild iodine deficiency (UIC: 100-150 μg/L) is associated with an increase in FT3，FT4 and TgAb levels in pregnant women.•Mild iodine deficiency may increase the risk of thyroid dysfunction in pregnant women.