GSTM1 and anemia (phenotype): Daily iron supplementation associated with ↑ Hb at term (MD 6.00 95% CI 2.75-9.25, high quality trials only included in MA) before & after birth and ↓risk of anaemia at term (RR 0.46; 95% CI 0.29 to 0.72, MA from 4 high quality trials)