We conducted a pilot study of associations between drinking water contaminated by inorganic arsenic (iAs), mostly <10 μg/L, and self-reported chronic diseases in 297 pregnant women. Adjusted for confounding variables, we identified a positive association between iAs and heart disease (OR = 1.63, 95%CI 0.81–3.04, p = 0.094), which was stronger for women living at their current residence ≥10 years (OR = 2.47, 95%CI 0.87–10.43, p = 0.058). Confounder-adjusted associations were also suggested for iAs with kidney disease (OR = 1.32, 95%CI 0.77–2.21, p = 0.265) and with high blood pressure (OR = 1.36, 95%CI 0.68–2.39, p = 0.300). A post hoc power analysis indicated the need for a larger study with more statistical power. [ABSTRACT FROM AUTHOR]