Prenatal inorganic arsenic (iAs) exposure is associated with pregnancy outcomes. Maternal capabilities of arsenic biotransformation and elimination may influence the susceptibility of arsenic toxicity. Therefore, we examined the determinants of arsenic metabolism of pregnant women in Bangladesh who are exposed to high levels of arsenic. In a prospective birth cohort, we followed 1613 pregnant women in Bangladesh and collected urine samples at two prenatal visits: one at 4–16 weeks, and the second at 21–37 weeks of pregnancy. We measured major arsenic species in urine, including iAs (iAs%) and methylated forms. The proportions of each species over the sum of all arsenic species were used as biomarkers of arsenic methylation efficiency. We examined the difference in arsenic methylation using a paired t-test between first and second visits. Using linear regression, we examined determinants of arsenic metabolism, including age, BMI at enrollment, education, financial provider income, arsenic exposure level, and dietary folate and protein intake, adjusted for daily energy intake. Comparing visit 2 to visit 1, iAs% decreased 1.1% (p <  0.01), and creatinine-adjusted urinary arsenic level (U-As) increased 21% (95% CI: 15, 26%; p <  0.01). Drinking water arsenic concentration was positively associated with iAs% at both visits. When restricted to participants with higher adjusted urinary arsenic levels (adjusted U-As > 50 μg/g-creatinine) gestational age at measurement was strongly associated with DMA% (β = 0.38, p <  0.01) only at visit 1. Additionally, DMA% was negatively associated with daily protein intake (β = − 0.02, p <  0.01) at visit 1, adjusting for total energy intake and other covariates. Our findings indicate that arsenic metabolism and adjusted U-As level increase during pregnancy. We have identified determinants of arsenic methylation efficiency at visit 1.

中文翻译：

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孟加拉国孕妇砷甲基化效率和尿砷水平的决定因素

产前无机砷 (iAs) 暴露与妊娠结局相关。母体砷生物转化和消除的能力可能会影响砷毒性的敏感性。因此，我们研究了暴露于高浓度砷的孟加拉国孕妇砷代谢的决定因素。在一项前瞻性出生队列中，我们对孟加拉国的 1613 名孕妇进行了追踪，并在两次产前检查中收集了尿液样本：一次在怀孕 4-16 周，第二次在怀孕 21-37 周。我们测量了尿液中的主要砷形态，包括 iAs (iAs%) 和甲基化形式。每个物种占所有砷物种总和的比例被用作砷甲基化效率的生物标志物。我们使用第一次和第二次访问之间的配对 t 检验检查了砷甲基化的差异。使用线性回归，我们检查了砷代谢的决定因素，包括年龄、入学时的体重指数、教育程度、财务提供者收入、砷暴露水平以及膳食叶酸和蛋白质摄入量，并根据每日能量摄入量进行调整。比较访视 2 与访视 1，iAs% 下降 1.1%（p < 0.01），肌酐调整后的尿砷水平 (U-As) 增加 21%（95% CI：15, 26%；p < 0.01）。两次就诊时饮用水砷浓度均与 iAs% 呈正相关。当仅限于调整后尿砷水平较高的参与者（调整后 U-As > 50 μg/g-肌酐）时，测量时的孕龄仅在第 1 次访视时与 DMA% 密切相关（β = 0.38，p < 0.01）。此外，DMA % 与第 1 次访视时的每日蛋白质摄入量呈负相关（β = − 0.02，p < 0.01），调整总能量摄入量和其他协变量。我们的研究结果表明，砷代谢和调整后的尿砷水平在怀孕期间会增加。我们在第 1 次访问中确定了砷甲基化效率的决定因素。