The quickest way to get women to rethink the issue is to threaten to give them what they want. Life begins at birth rather than conception? This applies to men also. Men will no longer be financially responsible for the child just because they were present at conception. You do NOT have a right to his DNA because it's his body! Furthermore, it was fluid when he left it there, not a child (kinda like the "tissue" argument).
Framed in this light, I think many women would reconsider.