GSTM1 and anemia (phenotype): In particular, compared to normal BP, elevated BP (OR 2.06, 95% CI 1.16–3.67), stage 1 hypertension (OR 3.28, 95% CI 1.68–6.41) and stage 2 hypertension (OR 2.12, 95% CI 1.09–4.10) were positively associated; compared to normal Hb, moderate anaemia (OR 0.44, 95% CI 0.19–0.99) was negatively associated; compared to primiparity, multiparity (OR 2.30, 95% CI 1.20–4.41) was positively associated; compared to not living with HIV, living with HIV (OR 0.47, 95% CI 0.30–0.74) was negatively associated.