GSTM1 and anemia (phenotype): However, in Ghana, the prevalence of anaemia (Hb <100 g L−1) decreased during pregnancy and was quite low (2–8%) by 36 gw, whereas in Malawi, the prevalence of anaemia was similar at enrolment and 36 gw and was higher at 36 gw (~20% at 36 gw) than in Ghana.