Manganese exposure through drinking water during pregnancy and size at birth: A prospective cohort study

• A wide range of manganese levels was found in the water consumed by pregnant women.
• Elevated water manganese (Mn) was associated with lower birth length.
• The association was significant in girls and also in boys of mothers with lowest hemoglobin concentrations.

The essential element manganese (Mn) might be toxic at excess exposure. We assessed the impact of elevated Mn exposure through drinking water during pregnancy on birth size in a population-based cohort(n = 1695) in rural Bangladesh. Concentrations of water Mn (median = 236 μg/L, range = 7.1–6336; n = 1177) and erythrocyte Mn (median = 30 μg/kg, range = 6.3–114; n = 758) were measured using ICP-MS. In regression analyses, newborns of women in the highest tertile of water Mn (median = 1495 μg/L) were 0.49 cm (0.20 SD) shorter (B = −0.42; 95% CI: −0.77, −0.08) than those in the lowest tertile (56 μg/L). The inverse association was significant in girls and also in boys of mothers with lowest hemoglobin values, likely due to higher absorption of Mn. Manganese concentrations in water and erythrocytes did not correlate, and the associations of the latter with birth size were less obvious. This study suggests that consumption of water with highly elevated Mn levels during pregnancy may impair fetal growth.