Dr Arnold Halpern, M.D., was a director of a Planned Parenthood abortion clinic in the United States. He told his story in the video "Eclipse of Reason", made by former abortionist Dr Bernard Nathanson, the co-founder of the National Abortion Rights Action League (NARAL).
"I felt 'licenced' to do abortions, because I didn't consider a foetus a real baby, until it reached 20-weeks gestation when women can feel the movement.
"About the late-1980s, a combination of factors made me reconsider being 'licenced'. Ultrasound was making the foetus more human, there was new knowledge about its development - and it was getting harder to think of the foetus as a "thing".
"It all came together when one day I walked into the abortion clinic and there 13 women waiting. Recently I had felt uncomfortable doing the abortions. I felt disgusted at myself.
"You see, I had started doing second trimester abortions and there was not only tissue coming out, but foetal parts, and to my horror I realised this is a baby coming out in pieces. I got so upset, that I just couldn't continue.
"When I looked at those 13 women and realised what I would have to do, I just walked out and left without doing the abortions. I never entered another abortion clinic again.
"I had finally got to a point where I couldn't look at those little bodies again.
"Now I recognise that there is no difference between a first-trimester abortion, a second trimester abortion, or a third trimester abortion, or even infanticide. It's the same human being in different stages of development.
"We have gone into a noble profession to be healers, and we lose sight of what we were called to do when we get into the killing business."