A Conceptions Right To Life is a false premis because it doesn't take all facts into consideration.
First: There are a lot of things that are "alive" and growing to reach some final potential. Being alive in the case of conception has that life having the potential to become a full person if it continues to evolve. A person is more than a few cells growing. A person has feelings and many other things that come along with development.
Let's try and remember that if one takes this fertilized cell idea as a full blow person than every woman on today's safe and effective Birth Control Pill is committing mass murder because the Pill contaminates the womb so that the ALREADY FERTILIZED EGG cannot implant and hence aborts.
I can't think of many people that really, seriously belive this is murder.
Secondly: You have a fully developed living breathing person with rights to consider here... the woman. No where in law can one person be legally forced to give up their personal body so something or someone else can get the benifit of it or even live for that matter.
In Example: If my brother needed a bone marrow transplant and I was the only person on earth that could save him... I'm not (and shouldn't be) legally bound to do anything against my will as far as giving up my body for use.
So we end up in a situation where someone that can live on their own and make an informed decision has that final decision of events over something that cannot.
So we can say that those first two cells are a person or anything else only because if everything went well, no disease, no severe birth defect, no miscarriage, not still born, not aborted etc. they would eventually be born and having personhood.
But until it is viable (reasonably able to live on it's own outside the womb) it doesn't have the same standing as a person with personhood. It's basically a legal difference... person isn't personhood.
