Hematopoisis in first month of life is

After bih, and during early childhood, hematopoiesis occurs in the red marrow of the bone. With age, hematopoiesis becomes restricted to the skull, sternum, ribs, veebrae, and pelvis. Yellow marrow, comprised of fat cells, replaces the red marrow and limits its potential for hematopoiesis. Reference: GHAI Essential pediatrics, 8th edition