I was somewhat surprised that a majority of the commenters seemed to be at odds with Akin's stance. I wonder if, with all of the moral issues which Catholics are used to opposing such as cloning, IVF, surrogate motherhood, etc. that the concept of embryo adoption suffers a certain guilt by association in the minds of many conservative Catholics, because it 'looks too much like' IVF or cloning.
My own instincts are with the second group--that it is morally permissible to adopt embryos in order to keep them from dying.
To my mind, the definitive moment of reproduction is conception. When that happens is when you have a new human being. What happens to it next is not reproduction, because the reproduction has already taken place and we have a new person. What follows (implantation in the womb and subsequent gestation) is simply caring for a new person who already exists and thus is not subject to the same kind of moral unalterability as the act of reproduction itself.
In other words, human reproduction is inviolable, which is why IVF (like adultery) is wrong, but most of what is happening during pregnancy is not reproduction. A new human is produced--and thus reproduction takes place--at the very beginning of pregnancy. What follows is growth, development, and care.
Whatever the reason, I think the reproduction followed by nurturing description which Akin uses is one of the main differences between Catholic teaching and mainstream American feeling these days. My impression is that many people envision all of early pregnancy or in extreme cases pregnancy as a whole as one long act of reproduction, which doesn't actually produce 'a baby' until very late in the process. This may make intuitive sense to many people at an emotional level, but it presents problems physically, since there is a continuity of existence throughout the development of the embryo/fetus/baby from conception to birth and beyond. From an empirical perspective (and though I by no means hold that the empirical perspective is the only or even the most important way of viewing the world -- it certainly is the best way we have of understanding the physical world around us) it is conception at which something clearly happens. What occurs after that is clearly development. A great deal of development to be sure, but development within a continuity of existence. Any other dividing line must be based upon how some external observer feels about the unborn child -- and I am deeply skeptical of any system which claims that what something is depends upon how others perceive it rather than upon its own being.