Which isn't the Social Conservative philosophy because if one doesn't have the basic rights of one's own existence protected, there is no place for any other rights. The Constitution clearly states that one can't be deprived of life without due process of law. That is something the State's have no say in under the 10th Amendment. That is a fundamental right you own that no legislative body should be able to take away (be it federal, state, or local). It is one of those things that pure 10thers miss by not understanding Madison's writings and the 10th Amendment. There was a clear line in the 10th between the States and 'Retained by the people'. As Madison pointed out in Federalist 45, what rights were given to the States were legislative roles of governance while the 'retained by the people' were rights clearly individual rights (speech, bearing arms, etc).
First I'd like to say I believe life begins at conception and I would support a Constitutional Amendment outlawing it and charging those who perform them AND the "mother" with Murder One.
That said, I believe the law is less than clear on when a "fertilized egg" transitions to "unborn baby". Viability outside the womb is only sometimes the the legally recognized transition. I would cite 3rd trimester abortion and the fact that if you kill a woman that is 8 months pregnant that you are charged with two murders.
Absent any clarity in the law as now written and despite your contention (along with many pro-life Freepers) that were talking "Equal Protection"...there is no such legal precedent and an immense body of precedent to the contrary.
For the most part, and it's grey, the law declares personhood as a born child or one that would be viable if born now. The exception being late-term abortions for whatever reason.