If a baby has anemia 4-8 weeks after birth, it may be caused by physiological anemia, which is a normal physiological reaction and does not need to be treated. Generally, the anemia will gradually ease after the baby is 3 months old. Pathological anemia in babies mainly includes iron deficiency anemia, hemolytic anemia, blood loss anemia, etc. It is mainly related to insufficient iron intake, malabsorption, congenital genetics and other factors: 1. Iron deficiency anemia: babies can show symptoms such as loss of appetite, pale skin, inattentiveness, etc. It is mainly due to insufficient nutrition or poor absorption and rapid growth of babies, resulting in iron, folic acid, vitamin B12 deficiency, thus triggering iron deficiency anemia. If supplemental food is not added in time when the baby is 6 months old, iron deficiency anemia can easily occur; 2. Hemolytic anemia: babies can show pale lips, skin, nail bed, skin mucosa, commonly due to congenital genetic factors, such as hereditary spherocytosis, glucose-6-phosphate dehydrogenase deficiency, thalassemia, etc. can lead to anemia in babies. In addition, acquired diseases, such as autoimmune hemolytic anemia, can also lead to the occurrence of anemia in babies; 3, blood loss anemia: for example, long-term gastrointestinal chronic blood loss, such as suffering from hookworm disease, ulcer disease, or nose bleeding, may lead to anemia in babies, manifested as pale face and cold extremities; 4, other: for example, acute leukemia, babies can appear anemia, fever, bleeding, lymph nodes swelling and other symptoms. If your baby has symptoms of anemia, it is recommended to take your baby to the pediatric department or the hematology department of the hospital in time to conduct routine blood tests under the guidance of the doctor to clarify the cause of the disease and then treat it accordingly.