GSTM1 and anemia (phenotype): Our estimate of low Hb (4%) was similar to a 2015 South Australian estimate of women with anaemia in pregnancy (6.6%).[30] International studies have found much higher rates of maternal anaemia with a global estimate of 38% in 2011.[31] The high proportion of women with a history of iron-deficiency anaemia in our population (15%), particularly in the low Hb group, suggest there may have been opportunities to correct low Hb due to iron deficiency before the pregnancy.