  I have a similar story to that regard. I was a pro-choice dude till my frosh year. I remember a friend who even confided with me a few times that she was going to abort her 4 month old fetus; she'd told her mom, and part, if not all, of it was based around fear of her father. But the incident that really got me thinking was the night before we at Pendleton H.S. left for a district acting compostition in Portland. We were performing our skits and monolgoues for an audience, and one was about this girl whose mother forced her to abort her child, and then ran away from her mother, who kept trying to find her and bring her home. The daughter wouldn't, since she'd killed off a living thing in her womb. It was all along those lines, and I lost all pretensions for abortion (including the for population control bit).
That piece of acting was especially powerful, and it gave me a very personal look at the whole issue. It is something living to me, regardless of its cognizance of its state, for it's growing and is a nutrient-needing being, possessing of a soul. That's how I feel. 
