Rescuing Unborn Children: Required and Right

January 18, 1987, John Piper preached a sermon to expose the evil of abortion. Since this sermon he has preached against abortion every year on the Sanctity of Life Sunday, which correlates with the dark anniversary of Roe v. Wade.
(link to sermon - Rescuing Unborn Children:  Required and Right)
Pastor John:
On December 19 eight of us from Bethlehem were among the 92 arrested while participating in a rescue at Planned Parenthood on Ford Parkway in St. Paul. [We] simply sat in front of the door to say by our action: without violence we will do what we can to stop child-killing here today.
Is that remarkable? Not very. But here’s something that is:
Liberty Ann Hinkle was born 3 and ½ months premature March 1987. She weighed 1 lb. 3 oz. She lived. I have a picture of her when she was born and one a year later. She is sitting up and smiling with a very lady-like bonnet.
Last week in St. Paul a woman 21 weeks pregnant paid to have the medical people kill her baby. What was the difference between these two babies? Perhaps a week in age. In one case the mother and medical people bent every effort for life. In the other they used their know-how to kill.

Wouldn’t you sit down in front of a door to separate a baby from a killer? 
(link to desiring God blog)