I don't see a sound scientific basis for considering the individual to begin at conception. I do not accept that the individual himself IS a body, or anymore harmed by a first trimester abortion than he is by his father practicing Onanism the week before conception. The volved wisdom after Wade vs Roe was that abortion was contraindicated after the second trimester of pregnancy. That's a scientific or medical basis. There is a world of difference between a possible organism and an actual one. The problem is by pushing that definition back further and further, you have decided on whatever basic grounds to elevate the interest of a life process within a host over the interest -- and self-determination -- of the host organism who is without question an operational, legal human being.
I think you should leave Roe vs Wade well enough alone, unless or until there is a clear scientific understanding available -- not just a religio-moral instinct -- on which to base a wiser proposal.