abortion and slavery

This from John Piper is timely given the celebration of our first black, pro-abortion president.

On January 12, 2009 Samantha Heiges, age 23, was sentenced to 25 years in prison for drowning her newborn in Burnsville, Minnesota. If she had arranged for a doctor to kill the child a few weeks earlier she would be a free woman.

What are the differences between this child before and after birth that would justify it's protection just after birth but not just before? There are none. This is why Abraham Lincoln's reasoning about slavery is relevant in ways he could not foresee. He wrote:

You say A. is white, and B. is black. It is color, then; the lighter, having the right to enslave the darker? Take care. By this rule, you are to be slave to the first man you meet, with a fairer skin than your own.

You do not mean color exactly? You mean the whites are intellectually the superiors of the blacks, and, therefore have the right to enslave them? Take care again. By this rule, you are to be slave to the first man you meet, with an intellect superior to your own.

But, say you, it is a question of interest; and, if you can make it your interest; you have the right to enslave another. Very well. And if he can make it his interest, he has the right to enslave you. ("Fragments: On Slavery")

There are no morally relevant differences between white and black or between child-in-the-womb and child-outside-the-womb that would give a right to either to enslave or kill the other.