I don't think anybody says that they are "pro-war," even if they are--they know it sounds bad.
What they do say, sometimes, is that the 'unborn' are most deserving of protection, since they are the least guilty of all humans, not having yet had a chance to do anything wrong. Logically, it's a bit unpersuasive, since the opposite is also true--what value is there in virtue that is completely untested? But it has a certain emotional appeal, I suppose.
Then again--looking at previous answers, it seems I need to reconsider the thought that no-one says they are 'pro-war!'