I agree all life is precious, but every embryo is not going to become a human life.  I am speaking from personal experience here.  That is just simple fact, they harvest a lot more eggs and sperm and create embryos than most couples are going to have implanted in the womb.  They shoot for 10-12, I know of very few families who plan to raise that many children, and many are not viable.  They get implanted, then rejected, or the technical term, reabsorbed into the woman's body.  Again, speaking from personal experience.  I want my unused embyos to be used to perhaps SAVE a life, than just have them be discarded, which is their only other fate.  I feel the same about organ donation if I were to die, I would want it (the organ) to further life because I DO believe life to be precious.