GSTM1 and anemia (phenotype): We defined anemia as hemoglobin concentration of 11.0 g/dL or less, since we previously saw high intraindividual variations between Hb 10.5 and 11.0 g/dL and there was a large group of women with hemoglobin between 10.5 and 10.9 g/dL (39/382; 10.2%).