I left work yesterday thinking of this question and I was about to write a response much like Karisma's. Although in my response I would use self-determination. Self-determination has the problem that the mother (except for rape cases) has willingly accepted the possibility of becoming pregnant. But then again millions of people willingly accept the possibility of heart disease by consuming junk food and all types of cancers from choices as clean cut as smoking up to vegeterianism. Should all of them pay? In that case aren't we all responsible for many of our health problems in some form or another? E.g. rode a bike in the rain, be refused antibiotics to die of pneumonia. Self-determination does apply because the mother did not become pregnant on purpose in order to kill a fetus. It was an accident and as long as you provide medical attention to careless drivers (we have all been a bit absent minded while driving so take the plank out of your own eyes) who may have killed others by mistake you cannot judge a woman who got careless one night in bed.
My bottom line is that yes abortion is a form of murder. But the mother's right to self-determination trumps the fetus' right to live. Medically, unfortunately, the fetus is a parasite. Wanted or not by the host it acts as a parasite it is therefore up to the host to have it removed or not. If the fetus could live outside the mother's body (in a jar or transplanted to another host) then we could start talking unborn rights untill then it has as many rights as any individual mother gives it.
This of course does not really take personal morality into account. Religion, education and other factors form a person's morality and whether abortion is moral or not in a personal level is up to each individual. Personal morality is just that tho personal, nobody has the right to impose it on others. On a side note I had an argument with two friends about the morality of adoption, their point is that the stigma associated with adoption (in Greece) makes it a bad choice, amusingly one (male) was anti-abortion and argued that the only option is to bring up the baby the other (female) was pro-abortion and argued that at this stage of their life abortion is the only humane choice.
