New England Journal vs. Unborn Human Life

This leading medical journal, long a leftist bastion, supports abortion by condemning the idea that a fetus is a “person” and therefore deserving of legal protection.
Problem: If unborn babies can be defined as “non-persons,” where DO we draw the line? What other categories of human life can be defined as less than human?
How long before we descend to the level of the Nazis, who defined whole groups as Untermenschen, subhumans who were “life unworthy of life” and a “drain on the Fatherland”?