Scientific evidence not available in 1973 now shows conclusively that life begins at conception (since part of the original Roe decision was based on inherent uncertainty about when life began - not a "personhood" question, and Maybe the 'personhood' argument is the right one (I feel it is). I honestly cannot comprehend how anyone, aside from improvable religious reasons, can say that the defining characteristic for human life is not being aware or thinking or sentient. Given that a baby is thinking and aware to a point, and a fertilized egg is not, there must be some point along the way where that changes and there is a human life. If you want to say just when there is life, than every cell in my body is a life and needs to be protected? It is ludicrous to say life and no more. This does not make abortion ok; it just changes the arguments a bit. EDIT: JFT, 40 million.