In same way a baby is not a teenager, but both are human lives. A zygote is not a baby, but a human life at a different point of development.
Whether or not we consider that human life deserving of legal protection is the real issue at hand.
Now, having acknowledged that, I don't think life is sacred. The tragedy of death stems from the pain and suffering one endures while dying and the loss experienced by those who cared about the one who died.
I don't think early term abortions are a tragedy. The embryo has not yet developed neural connections, and thus does not have enough awareness to "suffer" in it's death, and the only person who could have conceivably developed enough of an attachment to care and experience a feeling of loss (mourning) would be the woman who chose abortion.
Late term abortions are infanticide. If the only legal difference between a C-section and an abortion is if you actively kill it first...