Institute of Reproductive and Child Health, Peking University/ Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Beijing 100191, PR China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, PR China.
Department of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, PR China.
Environ Int. 2022 Jan;158:106965. doi: 10.1016/j.envint.2021.106965. Epub 2021 Nov 1.
Trace elements have various physiochemical functions in humans and are associated with the occurrence of preterm birth (PB). However, their mixed effects on PB risk have rarely been studied. We aimed to investigate the associations between hair levels of trace elements and PB risk among pregnant women. A nested case-control study with a prospective cohort was conducted in Beijing City, China. We included 82 women who had a PB [total PB (tPB)] as cases [including 40 with a spontaneous PB (SPB)] and 415 who had a term delivery as controls. Hair levels of the concerned trace elements were measured including endocrine disrupting metal(loid)s [EDMs; lead, mercury (Hg), arsenic, and cadmium] and nutritional trace metal(loid)s [NTMs; zinc (Zn), iron (Fe), copper, and selenium]. Logistic regression analysis was performed to estimate the odds ratios (ORs) for PB. Bayesian kernel machine regression (BKMR) was used to assess the associations between mixed exposure to the trace elements and PB risk. Significantly lower maternal hair concentrations of Zn and Fe were observed in the SPB cases than in the controls, whereas no differences for the other trace elements. Single-element modeling results suggested second-quartile Hg maternal hair concentrations, third-quartile Zn concentrations, and fourth-quartile Fe concentrations were associated with a reduced risk of tPB with adjusted ORs of 0.43 [95% confidence interval (CI): 0.21-0.87], 0.38 (95% CI: 0.18-0.82), and 0.48 (95% CI: 0.24-0.98), respectively, compared to first-quartile values. Similar results were obtained for SPB. According to the BKMR models, hair NTMs were significantly, monotonously, and inversely associated with the risk of SPB, after controlling for covariates and levels of the four EDMs. Fe and Zn contributed the most strongly to the association. We concluded that maternal higher levels of NTMs, especially Fe and Zn, may reduce the risk of PB.
微量元素在人体中具有各种理化功能，与早产（PB）的发生有关。然而，它们对 PB 风险的混合影响很少被研究。我们旨在研究孕妇头发中微量元素水平与 PB 风险之间的关系。在中国北京市进行了一项嵌套病例对照研究，采用前瞻性队列研究。我们纳入了 82 名发生 PB（总 PB[tPB]）的女性，其中 40 名发生自发性 PB（SPB），作为病例；415 名足月分娩的女性作为对照。测量了有关微量元素的头发水平，包括内分泌干扰金属（EDMs；铅、汞（Hg）、砷和镉）和营养性微量元素（NTMs；锌（Zn）、铁（Fe）、铜和硒）。采用 logistic 回归分析估计 PB 的比值比（OR）。采用贝叶斯核机器回归（BKMR）评估混合暴露于微量元素与 PB 风险之间的关系。SPB 病例的母体头发中 Zn 和 Fe 的浓度明显低于对照组，而其他微量元素则没有差异。单元素模型结果表明，第二四分位数 Hg 母体头发浓度、第三四分位数 Zn 浓度和第四四分位数 Fe 浓度与 tPB 风险降低相关，调整后的 OR 分别为 0.43（95%CI：0.21-0.87）、0.38（95%CI：0.18-0.82）和 0.48（95%CI：0.24-0.98），与第一四分位数值相比。SPB 也得到了类似的结果。根据 BKMR 模型，在控制协变量和四种 EDM 水平后，头发 NTMs 与 SPB 风险呈显著、单调和负相关。Fe 和 Zn 对关联的贡献最大。我们得出结论，母体较高水平的 NTMs，特别是 Fe 和 Zn，可能降低 PB 的风险。
