You'll need to consider your strong views about abortion when you consider your specialty and your employer. If you don't want to participate in abortions, don't work in a unit where they are done. Few (if any) schools
would force a student to participate in one involuntarily.
This raises another issue, however. How will you deal with patients who are considering abortion or who have had one in the past? This is the type of patient you might encounter in any number of settings -- a family practice clinic, a general med/surg floor, etc. Will you be able to accept and respect that patient's decision and to give her good care even though you disagree with her decision?
That's an issue we all face at some times during our career. Can you give your best care when the patient is making choices you don't approve of? (sexual practices, drugs, religion, criminal activity, etc.)