A Hb concentration of less than or equal to 100 g/L, and a haematocrit of less than 32% are risk factors for maternal transfusion (Rukuni et al., 2016; Ahmadzia et al., 2018) and neonatal morbidity including preterm birth, low birthweight, and potentially perinatal mortality (Nair et al., 2016; Rahman et al., 2016; ACOG practice bulletin no. 95: anemia in pregnancy, 2008). Here, GSTM1 is linked to anemia (phenotype).