Personally I could never have an abortion - and I can state that for definite, as I was in a postition in 2004 when I was sure that I was pregnant and I really had to make up my mind (my period was late, unprotected sex, etc etc). So I know for myself that I couldn't do it, and I do personally believe that it is killing a baby.
BUT I believe that everybody should have the option to make that choice for themselves. If abortions were illegal then girls would resort to back street abortions and that would be really dangerous, both for the baby and the mother. It would lead to pregnancy becoming a shameful thing, which it isn't. So I fully believe that abortion should be legal and people should be able to choose.