Arsenic exposure and metabolism in relation to blood pressure changes in pregnant women.

ABSTRACT

Arsenic is concerned with cardiovascular diseases including hypertension, atherosclerosis, and endothelial dysfunction. However, what effects the arsenic exposure and the arsenic metabolism have on hypertensive disorders of pregnancy (HDP) and blood pressure changes during pregnancy remain largely unknown. Our goal was to assess the associations of arsenic exposure and arsenic metabolism with HDP and blood pressure changes in pregnant women through a prospective birth cohort study. A total of 1038 women who were pregnant (52 HDP, 986 non-HDP participants) were included. Arsenic species of spot urine samples collected at three trimesters were measured, which included inorganic arsenic (iAs), monomethylated arsenic (MMA), and dimethylated arsenic (DMA). Arsenic metabolism was evaluated as the percentages of iAs, MMA, and DMA respectively (i.e., iAs%, MMA%, and DMA%). Outcomes were HDP and systolic, diastolic, and mean arterial pressure changes during pregnancy. We employed mixed linear models to investigate the relationships between arsenic exposure and arsenic metabolism with changes in blood pressure during pregnancy. Poisson regression with a robust error variance with generalized estimating equations (GEE) estimation was used so that the associations of arsenic exposure and arsenic metabolism with HDP could be estimated. In this study, there was a significant relationship between the concentrations of urinary DMA and the weekly change in systolic blood pressure (SBP) (ß = -0.10; 95% CI -0.15, -0.05), diastolic blood pressure (DBP) (ß = -0.07; 95% CI -0.11, -0.02) and mean arterial pressure (MAP) (ß = -0.08; 95% CI -0.12, -0.04). Higher DMA% was accompanied with lesser weekly increase in SBP (ß = -0.05; 95% CI -0.10, 0.00), DBP (ß = -0.06; 95% CI -0.10, -0.01) and MAP (ß = -0.06; 95% CI -0.09, -0.01) during pregnancy. There was a positive association with the highest tertile of iAs% and weekly change of SBP (ß = 0.08; 95% CI 0.03, 0.13), DBP (ß = 0.07; 95% CI 0.03, 0.11) and MAP (ß = 0.07; 95% CI 0.03, 0.11). No association was found between each arsenic specie and arsenic metabolism marker in the first trimester and risk of HDP. Arsenic exposure and arsenic metabolism during pregnancy potentially change blood pressure of pregnant women. These findings may be significance as even modest elevation of blood pressure can increase the risk of cardiovascular disease.