Human rights are a special sort of inalienable moral entitlement. They attach to all persons equally, by virtue of their humanity, irrespective of race, nationality, or membership of any particular social group.If these rights are had "by virtue of [one's] humanity," then they are had by all humans, including the human embryo and fetus. Every person who embraces the above concept of human rights (I hope everyone does) rationally must acknowledge what follows from that concept: human rights for the unborn human killed by abortion.
I see one possible escape route for someone who embraces the above concept of human rights but who denies that the unborn has basic rights. One could take issue with my interpretation of "human," contending that while the unborn is biologically human -- i.e., a member of the species Homo sapiens -- he or she is not human in the moral, social or metaphysical sense that we mean when we talk about human rights.
The problem is that any such criterion for "humanity" -- other than being a member of the human species -- provides no basis at all for human equality, which is an important part of the concept of human rights (see above). We are only equal in virtue of the kind of thing we all are (what we all have in common), and we share that same thing in common with the human embryo and fetus.
So the traditional understanding of human rights is incoherent unless unborn human beings are included in the community of rights-bearing individuals.