Zeev, How can you have a universal definition of "when life starts" (rather then a general definition of life, in case of abortion) when that definition is purely religious and each religion has its own definition, all the way from catholicism with life starts upon conception, to judaism with life starts with the first independent breath of the newborn?
I suppose an unborn baby could be considered "three-fifths" of a life. At least there would be legal precedent for the "three-fifths" figure.
Now before you bring up more relativism, you might want to consider why abortion is even an issue in the first place. Is it because we have an epidemic of rapes and medical problems for which abortion is seemingly the "only" way out? Or is it because of society's more liberal attitudes toward sex? Maybe that's what's causing people to start defining an unborn life in terms of their own convenience. Then they can simply blur the issue with differing religious views, even twisting Scripture in the process, all in an effort to avoid the moral responsibilities (both individual and societal) of pregnancy.
Just remember that no expectant mother ever refers to her unborn child as a "fetus."
Tenchu