The ability to have an abortion should be based on two things, a woman's choice about her body, and the realtive frequency that sadi woman uses abortion as a form of birth control in lieu of condoms, etc.
As in, a woman should have the right to choose what she does with her body, to a certain extent, but I am sure that such procedures eventually take their toll on the body in question after too many of them. Just like a patient is perscribed medication for a set amount of time, so too shouyld the amount of times a woman has abortions be limited to a safe number for their body.
After all, if you don't have your health, you don't have anything.