<prompt> Blood is produced in first six months in fetus in?LiverSpleenBone marrowNone  <response>: Ans. is a i.e., LiverErythropoiesis sitesIntrauterine0-10 weeks - Yolk sac10 weeks - 5 months - Liver major organ and spleen5 month onward - Bone marrowAfter bihUpto 20 years - Bone marrow of all bones After 20 years - Flat bones of axial skeletal and proximal end of humerus and femur. 