GSTM1 and anemia: It also significantly improved mean Hb (SMD: 0.19, 95% CI: 0.12, 0.26) and reduced anemia prevalence (RR: 0.90, 95% CI: 0.85, 0.96) and VLBW (RR: 0.38, 95% CI: 0.16, 0.87).