Inclusion criteria:-Adult and pediatric patients with a diagnosis of b-thalassemia major or transfusion-dependent b-thalassemia intermedia;-Regularly transfused for at least 12 consecutive months at the Center from January 1989 to 6 th November 2018.In patients who underwent bone marrow transplant, we collected pretransplant data, provided that they were regularly transfused for at least the 12 previous months at the Center.Exclusion criteria:-Adult and pediatric patients with non-transfusion-dependent thalassemia intermedia;-Patients with thalassemia major and a condition of autoimmune hemolytic anemia;-Patients with transfusion-dependent b-thalassemia intermedia receiving hydroxyurea;-Patients with b-thalassemia major or intermedia since the inclusion in erythroid maturation agents' clinical studies (i.e., luspatercept and sotatercept);-Patients with chronic kidney disease; -Patients that were not followed and regularly transfused at the Center for at least 12 consecutive months;-Patients followed at other Centers, whose data were recorded in WebThal in occasion of annual LIC by SQUID assessment at the Center.For female patients who underwent pregnancy, we excluded from analysis any pregnancy period, calculating backwards from childbirth to conception.