Bruises on the baby’s body may be caused by soft tissue contusions, or by diseases such as acute leukemia and immune thrombocytopenia. 1. Soft tissue contusion: If the baby has recently been hit or struck by a blunt external force, resulting in blood infiltration into the subcutaneous tissue, which can then cause bruising. 2. Acute leukemia: the etiology of the disease is not yet clear, but the current clinical opinion is related to viral infection, abnormal immune function, ionizing radiation, genetics and other factors, most of the children in the early stage of the bleeding symptoms, which can be manifested as bruises or petechiae on the body. Anemia and fever may also occur. 3. Immune thrombocytopenia: This disease is mainly caused by increased immune-mediated platelet destruction and insufficient platelet production by megakaryocytes, and is mostly related to viral infections and genetic factors. Typical symptoms are bleeding of the skin and mucous membranes, such as purple spots, petechiae, ecchymosis, etc., so there will be bruises on the body of the affected children. There may be other reasons for the bruises on the baby’s body, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment under the guidance of the doctor.