Human beings with their parts of bodies have been made honourable. It is not right to buy or sell them, or buy or sell or to gift their parts, it amounts to an insult to them. Secondly, humans are not the owners of their body parts; it is Allah Almighty who is the owner, therefore we can not sell and gift the things which we do not possess.
As far as blood donation is concerned, it is allowed only in a state of emergency and compulsion, as this is the case with milk.
If some woman is too sick to bear pregnancy or fears her life in case of delivering a baby, then in such cases abortion can be advised, but it is not allowed in general conditions.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband