GSTM1 and anemia (phenotype): This study found that the Group A had a statistically significant difference in the incidence of anemia and iron deficiency before delivery compared with the Group B (P < .001), and it was found that the Group A had a higher Hb level before delivery (β: 6.693, 95% confidence interval: 5.691–7.696) and those with pre-delivery SF ≥ 30 μg/L had a higher rate of recovery and a faster recovery time (hazard ratio: 10.77, P < .0001).