Ambient particulate matter, maternal thyroid function, and birth weight: A mediation analysis

Yuting Gong; Yueshu Zhao; Xiaoan Zhang; Xin Zhao; Hui Chang; Jia Huang; Zengli Yu; Huanhuan Zhang; Hongyan Liu

doi:10.1016/j.ecoenv.2023.115420

Ambient particulate matter, maternal thyroid function, and birth weight: A mediation analysis

Ecotoxicol Environ Saf. 2023 Oct 1:264:115420. doi: 10.1016/j.ecoenv.2023.115420. Epub 2023 Sep 1.

Authors

Yuting Gong¹, Yueshu Zhao², Xiaoan Zhang², Xin Zhao², Hui Chang², Jia Huang³, Zengli Yu⁴, Huanhuan Zhang⁵, Hongyan Liu⁶

Affiliations

¹ Department of Medical Genetics, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, Zhengzhou, China; School of Public Health, Zhengzhou University, Zhengzhou, China.
² The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
³ Department of Medical Genetics, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, Zhengzhou, China.
⁴ School of Public Health, Zhengzhou University, Zhengzhou, China.
⁵ School of Public Health, Zhengzhou University, Zhengzhou, China. Electronic address: zhanghh@zzu.edu.cn.
⁶ Department of Medical Genetics, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, Zhengzhou, China. Electronic address: liuhongyanqhhy@126.com.

PMID: 37660528
DOI: 10.1016/j.ecoenv.2023.115420

Abstract

Background: Birth weight (BW) is an indicator of fetal growth and development. Previous studies showed inconsistent results on the association of ambient particulate matter (PM) exposure with BW, and the role of maternal thyroid function has not been clarified.

Methods: We recruited 1711 gravidas between 2017 and 2019 in Henan, China. All participants were followed up until delivery. Daily concentrations of PM, including PM_2.5 and PM₁₀, were evaluated by using the spatial-temporal model. Maternal thyroid hormone (TH) levels were quantified by electrochemiluminescent microparticle immunoassay. Linear regression models were employed to examine the association among PM, BW, and maternal TH. Mediating effects of maternal TH interrelated with PM exposure on BW were investigated by causal mediation analyses.

Results: A total of 1049 gravidas were identified. We found that per 10 µg/m³ increase in PM_2.5 and PM₁₀ were associated with a decreased BW of 9.941 g, and 7.758 g (PM_2.5: 95 %CI: -18.184, -1.698; PM₁₀: 95 %CI: -14.436, -1.080). An inverse correlation of maternal FT4 levels with BW was found, with the pooled β of -319.983 g (95 %CI: -483.216, -156.750). We found a prominent positive correlation between gestational FT4 and PM exposure (PM_2.5: β = 0.004, 95 %CI: 0.001, 0.007; PM₁₀: β = 0.003, 95 %CI: 0.000, 0.006). Mediation analysis found that FT4 levels mediated the relationship between maternal PM exposure and BW, ranging from 5.55 % to 15.86 %.

Conclusions: Maternal PM exposure may induce a reduction in newborn BW by affecting the maternal TH concentrations.

Keywords: Birth weight; Mediation analysis; Particulate matter; Thyroid function.

MeSH terms

Birth Weight
China
Fetal Development
Humans
Infant, Newborn
Mediation Analysis*
Thyroid Gland*