Here are bullet points which summarize “The Morality of Killing Human Embryos”  by the philosopher Bonnie Steinbock:

• Are embryonic stem cells persons? Do they have moral status?
• Some things don’t have moral status—rocks—some things have more status than others—people than fish.
• People have moral status because they’re homo-sapiens.
• But when do they become human organisms?
• Some say at conception, but this is at odds with the facts of modern biology.
• Biologically, a genuine and unique organism presents itself at implantation—at about 14 days.
• And biological humanity does not imply moral status—as the examples of extraterrestrials and persons in vegetative states show. Some humans aren’t people, and some people aren’t humans.
• One could object to #7 by asking why should we limit moral status to persons.
• Might there be a middle ground between the biological and personhood views of moral status?
• We may think of moral status as corresponding with having interests or a stake in something.
• A being must have interests to have moral rights and status.
• Non-conscious beings do not have interests, nothing matters to them.
• And we do have a good idea of what it’s like to be conscious—conscious beings have interests.
• Embryos do not have consciousness or interests and hence no moral status.
• What about the argument that it was in one’s interest not to have been killed as a fetus?
• Steinbock counter that one never was an unconscious fetus, one comes to be when one is conscious.
• Steinbock also argues that it does not matter to you if you are aborted before you are conscious.
• At any rate, embryos outside of bodies have no future.
• Most of these embryos have no future even if implanted.
• Cloned embryos have no chance of have a future, hence they are even less morally problematic.
• It is morally acceptable to use embryos in research because they have no moral status.