GSTM1 and anemia: BW, LBW, GA at birth, preterm, SGA, Hb, anemia, length, length‐for‐age z‐score, stunting, weight‐for‐age z‐score, underweight, weight‐for‐length z‐score, wasting, BMI z‐score, thinness, ponderal index, head, chest, waist, hip circumferences, MUAC, biceps, and triceps skinfold