Pro-life is this: A friend has 10 siblings. He's also one of over 150 cousins.
Pro-life and anti-abortion are often very different categories.
The former is blessed whose quiver is full, leads a quiet life, works with their hands and minds their own business. Never heard of "terrorists" in this camp.
The latter are known as activists some of whom have used lethal force in an attempt to end abortion. Perhaps these are the few "terrorists" to which NPR refers.