Our current objective was to examine the associations between baseline maternal preconception Hb concentrations (primary exposure) and anemia with child health and development from birth through 6–7 y, namely, 1) birth outcomes (birth weight, birth length, preterm, gestational age, or SGA); 2) child Hb at 3 mo, 6 mo, 12 mo, and 24 mo; and 3) motor and mental development at 12 mo and 24 mo and cognitive functioning at 6–7 y. Here, GSTM1 is linked to anemia.