In addition, we have examined factors associated with anemia at baseline in our study population [50] and found that beyond ferritin concentration, being an ethnic minority (-0.24 mg/dL compared with the Kinh ethnic majority), number of children (-0.17) and socioeconomic status (0.09) were directly associated with Hb concentration (P<0.05). Here, GSTM1 is linked to anemia (phenotype).