The best sort of introduction to an emotional issue like abortion is a story. If possible, I suggest a real story, but it could also be a made-up story, which I call a "typical scenario" which would explain the problem and make it vivid for the reader. In this issue, it could be the story of a woman who finds herself in a crisis pregnancy. End the story with the question of your essay. Here are some possible questions:
1. What should a woman in a crisis pregnancy do?
2. How can we best help women who have crisis pregnancies?
3. How can we best advise friends who have a crisis pregnancy?
4. Is abortion ever a right choice?
5. Should we change abortion laws, and if so, how should they be changed?
My favorite book on this issue is called "Real Choices" by Frederika Matthews-Green. You don't actually have to read the book because she writes on her blog about this issue also. What I like about her work is that she takes the issue in a different direction by interviewing many women who have had abortions to find out what they really thought at the time that they were facing this crucial decision and how their decision affected them afterward.