Associations of Maternal Urinary Cadmium with Trimester-Specific Blood Pressure in Pregnancy: Role of Dietary Intake of Micronutrients.

Previous studies revealed associations of urinary Cd (U-Cd), a chronic Cd exposure biomarker, with blood pressure (BP) in non-pregnant adults. However, the evidence regarding trimester-specific blood pressure in pregnancy and U-Cd and effect modification by dietary intake of micronutrients is scarce. We randomly selected 653 women from the Omega Study cohort. U-Cd was quantified by inductively coupled plasma mass spectrometry. Trimester-specific, systolic (SBP) and diastolic blood pressure (DBP) were determined employing standard protocols and mean arterial pressure (MAP) was also calculated. Associations of SBP, DBP, and MAP with U-Cd tertiles (≤0.21; 0.22-0.41; ≥0.42 µg/g Cr) were assessed using multivariable linear regression models. We also explored effect modification by pre-pregnancy BMI (≤25 or >25 kg/m2) or low/high micronutrients intake. After adjusting confounders in women with elevated (upper tertile) as compared with those with low (lowest tertile) U-Cd (≥0.42 vs. ≤0.21 µg/g Cr, respectively) had reduced third trimester MAP (-1.8; 95 % confidence interval (CI) = -3.1, -0.5 mmHg) and second trimester MAP (-1.1; 95 % CI = -2.3, -0.03 mmHg). A significant decrease in third-trimester MAP associated with increased U-Cd was observed only among normal/underweight women (BMI ≤ 25 kg/m2) and women with high dietary intake of micronutrients (calcium, magnesium, zinc, and selenium). Notably, U-Cd concentrations increased with the increased consumption of zinc and non-heme iron food sources. No significant differences in U-Cd concentrations were found in preeclamptic women compared with non-preeclamptic women. Our study provides evidence that dietary intake of micronutrients should be taken into account when assessing the health effects of Cd in pregnant women.