Hi Justin, thanks for your comment.
'Suffer' is perhaps the wrong word to use for the unborn - by 'suffer' I meant to suggest that, by choosing not to have children, a potential person is deprived of their life.
My argument rests upon the notion that there are opportunity costs to all our actions, and that there is some degree of responsibility that rests upon us for that reason. My thinking here is influenced by Derrida, especially where he speaks of our responsibility to 'all other others'. It isn't so much that their feelings are relevant here; it is that we affect them with our choices. To me, this thinking partly explains the gravity of the birth-striker movement itself.