How does the formation of blood in adults differ from that in infants?

In adults, blood formation, or hematopoiesis, primarily occurs in the bone marrow, where stem cells differentiate into various blood cell types. In infants, particularly during the first few months of life, blood formation takes place mainly in the liver and spleen before transitioning to the bone marrow as they grow. Additionally, infants have a higher proportion of fetal hemoglobin, which is gradually replaced with adult hemoglobin as they mature. This shift reflects the changing oxygen transport needs as the infant's physiology develops.