Yes, absolutely. Because it is their body and they have a right to decide what happens with it, including growing a baby (or not).
I personally would not have an abortion, but I don't think it's my place to say that someone else shouldn't have the choice. I don't know anyone else's circumstances.
All of that being said, I am definitely a believer in putting a time limit on it. Here it's 20 weeks. The number of weeks that people are comfortable with would probably vary quite a bit (I think 20 weeks is a bit late myself) but I think it's good to have some maximum number implemented at all.