Three-month-old baby anemia may be aplastic anemia, but the possibility is small, the vast majority of cases are still iron deficiency anemia, thalassemia, hemolytic anemia and so on. 1. Aplastic anemia: this disease can be caused by genetic factors, that is, congenital aplastic anemia, manifested as bone marrow hematopoietic hypoplasia, hemorrhage, pancytopenia, anemia, infections and so on. Therefore, anemia in three-month-old babies may also be caused by this disease. However, this disease is clinically rare. Parents do not need to worry too much 2. Thalassemia: Thalassemia is a genetic disease, which can be caused by parents carrying disease-causing genes to their babies, and can be clinically treated by iron removal and other methods. 3. Iron deficiency anemia: due to the rapid growth and development of babies, iron demand is greater, poor absorption and other causes of iron relative lack, causing iron deficiency anemia. 4. hemolytic anemia: such as suffering from hereditary spherical erythrocytosis and other diseases, can cause the baby to appear hemolytic, thus occurring anemia. Cause 3 months baby anemia for many reasons, not necessarily just aplastic anemia, if necessary, can improve the bone marrow aspiration biopsy, clear cause of disease to be targeted treatment as prescribed by the doctor.