Covariates

Information about the mothers’ background characteristics [maternal age, education (number of years of formal schooling), parity, and BMI in early pregnancy, and smoking and alcohol consumption during pregnancy] was obtained at enrollment in MINIMat. None of the mothers smoked or consumed alcohol. Family SES at the follow-up at 9 y of age was estimated via a wealth index, based on information concerning family ownership of assets, housing structure, and dwelling characteristics (Gwatkin et al. 2000). This information was obtained from the Health and Demographic Surveillance System (HDSS) in Matlab, which is administrated by the icddr,b. At the 9-y-of-age follow-up, we also collected information on the number of children in the household and birth order. Season of sampling of blood was categorized as pre-monsoon (January–May), monsoon (June–September), or post-monsoon (October–December). The children’s plasma concentration of ferritin, which has been shown in adults to affect cadmium absorption (Berglund et al. 1994), was measured using Cobas e601 autoanalyzer (Roche Diagnostics); the inter-assay coefficient of variation was 1.9%. The cutoff for ferritin deficiency was set at 15μg/L (WHO 2011b). In addition, hemoglobin (Hb) was measured in whole blood with a HemoCue photometer (HemoCue AB). Anemia was defined as having a Hb concentration <115g/L (WHO 2011a).