By saying "people have a choice" you are automatically saying an unborn child is not a person. Now, i recognize you did not use those words, but it is implied because the only one allowed to make a choice is the one giving birth, the one being given birth to has no say. Care to explain why you think an unborn child is less than human, or at the very least, less than a person?
What about a rape conception, or a mother that finds out she's 2 months pregnant after a long coke binge.
If the child is past the first term, then yeah, that's not cool, but I think if you catch it early enough it's ok.
Just to note, I was 19 when I knocked up my 17 year old girlfriend, and I called abortion!! She said no, so I said Ok. We're now married, and have 2 kids. I am super glad she said no, but I still believe that it is unconstitutional to force a mother to have a child that she is in no position to raise. Adoption is great, but I would never expect a raped mother to carry that baby, nor is it fair for a deficit child to be born because a mother did drugs. Also, what about health complications? Should a mother carry a baby that will kill her? A life for a life?
These aren't even the majority of abortion cases, but these are the cases that I care to defend.