Serious defects in the living conditions of the vast majority of people in the tropics, rather than racial factors, are the underlying reasons why anaemia is common, why malaria is rampant and why the complications of sickle cell disease are so serious. Mass illiteracy, poor environmental hygiene and widespread poverty with all their implications explain why malaria eradication programmes have so far failed in tropical Africa and why basic health-care schemes have been difficult to establish. Pregnant women are very vulnerable to the effects of anaemia, malaria and sickle cell disease. However, appropriate use of folic acid and iron supplements as well as malarial chemosuppression succeeds in maintaining haemoglobin concentrations at reasonable levels during pregnancy. If, for whatever reason, the haemoglobin level falls to under 4.4 g/dl or the haematocrit value is 0.14 or less, anaemia becomes an obstetric emergency. Both maternal and fetal mortality rise sharply, maternal death being due to anaemic heart failure, fulminating bacterial infection and shock from even small loss at delivery or abortion. With the haemoglobin concentration as low as 4.4 g/dl, blood transfusion greatly improves maternal but not necessarily fetal prognosis. Additional cause of morbidity in sickle cell disease is painful crises, the control of which remains largely unsatisfactory. Now that sickle cell disease can be diagnosed early in intrauterine life the idea of aborting the affected fetuses as a means of controlling or reducing sickle cell disease is well within the means of developed countries, but it is a line of approach which developing countries cannot afford at present.