Background

The human placenta is vulnerable to environmental pollutants, but the associations between exposure to multiple, correlated metals and placental characteristics have not been studied.

Methods

The current study population was derived from the Hangzhou Birth Cohort Study. Whole blood and urine samples were collected from mothers during 20–28 gestational week. The concentrations of 11 metals in blood and 11 metals in urine were evaluated by inductively coupled plasma mass spectrometry. The data on placental characteristics and birth weight were retrieved from medical records. The elastic net (ENET) model combined with unpenalized regression model was employed to estimate the relationship between levels of metals and placental characteristics (placental weight, chorionic disc area, chorionic disc eccentricity, placental thickness, placental-fetal birth weight ratio) and birth weight. Mediation analysis was performed to explore the mediated effect of placenta on the association of prenatal metals exposure with birth weight.

Results

Among 512 participants with urine metal levels, the ENET model retained Cadmium (Cd) and Selenium (Se) for placental weight. Further unpenalized regression model including Cd and Se simultaneously showed that one-unite increased natural-logarithm (ln)-transformed urine creatinine corrected (CC) Cd levels was associated with reductions in placental weight of −7.2 g (95% confidence interval (CI): −14.0, −0.4). Among 483 participants with blood metal levels, similarly, blood Cd levels were negatively associated with placental weight (β = −7.5, 95% CI: −17.0, 1.9). Furthermore, mediation analysis demonstrated that urine CC-Cd level was associated with a 21.3 g decrease (95% CI: −42.0, −2.5, p = 0.024) in birth weight through a reduction in placental weight, while blood Cd levels presented a negative association at borderline significance.

Conclusion

Our findings suggest a mediation effect of the placenta in the relationship between prenatal Cd exposure and lower birth weight. Additional studies with repeated assessment of exposure and more placental parameters are warranted to confirm this relationship.

中文翻译：

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杭州出生队列产前重金属暴露与胎盘特征和出生体重的关系：基于弹性网回归的多污染物模型。

背景

人类的胎盘易受环境污染物的影响，但尚未研究多种相关金属的暴露与胎盘特征之间的关系。

方法

当前的研究人群来自杭州出生队列研究。在妊娠20–28周期间从母亲那里采集全血和尿液样本。通过电感耦合等离子体质谱法评估血液中11种金属的浓度和尿液中11种金属的浓度。胎盘特征和出生体重的数据是从医疗记录中获取的。用弹性网（ENET）模型与未惩罚回归模型相结合来估算金属水平与胎盘特征（胎盘重量，绒毛膜间盘面积，绒毛膜间盘偏心率，胎盘厚度，胎盘胎儿出生体重比）和出生体重之间的关系。 。进行了中介分析，以探讨胎盘对产前金属暴露与出生体重的关联的介导作用。

结果

在512名尿液中金属含量较高的受试者中，ENET模型保留了胎盘重量中的镉（Cd）和硒（Se）。进一步的无铅回归模型（包括Cd和Se）同时显示，将自然对数（ln）转换的尿肌酐校正（CC）Cd水平增加一倍，可使胎盘重量减少-7.2 g（95％置信区间（CI）） ：-14.0，-0.4）。同样，在483名血液中金属含量水平的参与者中，血液Cd水平与胎盘重量呈负相关（β= -7.5，95％CI：-17.0，1.9）。此外，调解分析显示尿液CC-Cd水平降低21.3 g（95％CI：-42.0，-2.5，p 胎盘重量的降低使出生体重= 0.024），而血液中的Cd水平在临界水平上呈负相关。

结论

我们的研究结果表明胎盘对产前Cd暴露与低出生体重之间关系的调节作用。有必要对暴露进行反复评估和更多胎盘参数来进行其他研究，以证实这种关系。