We investigated the effectiveness and safety of intravenous ferric carboxymaltose versus oral ferrous sulphate on anaemia and iron deficiency among pregnant women in Nigeria.<h4>Methods</h4>We did a multicentre, open-label, parallel, randomised controlled trial of pregnant women (aged 15-49 years) with haemoglobin (Hb) concentrations of less than 10 g/dL at 20-32 weeks' gestation from 11 primary, secondary, or tertiary health facilities in Nigeria (five in Lagos and six in Kano). The gene discussed is GSTM1; the disease is anemia.