David Schraub asks on his blog:
One important question in [the abortion] debate is when life begins. Pro-lifers have a very simple answer: at conception. Pro-choicers have a bevy of objections to this.
I’ll bite.
I’m a pro-choice anti-abortion person. In other words, I’d consider “abortion for convenience” to be tantamount to murder. However, I’d also consider an abortion to protect the mother’s health (physical or mental) to be tragic, but understandable.
But above all, I believe the decision of whether an abortion is appropriate is best left to the mother, her chosen doctor, and any other person(s) she wishes to involve. You, me, and the government have no place interfering.
With that background out of the way — when does life start? That’s easy — it starts at conception.
However, that’s not the right question to be asking. The better question should be, when does a person begin to merit the rights associated with being human?
That question is a more challenging one to consider. One could argue that, at least from a US-centric view, a person doesn’t receive the rights of a human until age 21…but that seems a bit extreme.
I used to subscribe to a rather pithy statement — “the rights of the born trump the rights of the unborn”. It’s succinct and encompasses a whole range of concerns. However, I have also wondered if that pithy phrase opens the door to possible abuse.
Consider a woman who is 9 months’ pregnant, just about ready to deliver. If she insisted on aborting the child just before birth “just because”…well, that would probably be OK with the concept of “the rights of the born trump the rights of the unborn”…and that doesn’t seem quite right.
I think now that if I had to draw a line, I would put it at the point of viability. If the unborn child could live (albeit with medical assistance) outside the womb, and have a reasonable chance of surviving and leading a rewarding life… well, one could argue that it is more morally correct to opt for early delivery rather than an abortion.
There’s still something about that position that bothers me…but that’s where my head is at right now.

As a prolifer myself I find your explanation about viability reasonable; though characteristics commonly assigned even to newborns are largely present even in early foetal development including before the stage of viability it is important to note that we may be reaching a maximum limit of viability for premature births, somewhere in the 20th to 25th week from conception.
On a nonrelated note I just viewed your plans for Memphis freeways in 2020 and wonder if it might be better to integrate TNpri385 and TNsec304 into an I-269 and possibly extend that as a loop round Memphis area including the West Memphis AR, or at least open an I-469 loop for the western Memphis metro region and have the I-269 terminate at the I-22 (which I would extend beyond Birmingham to Columbus GA) and free up the TNpri385 and TNsec304 for other routes either in the area or elsewhere. I seriously doubt that US78 would be decommissioned however as more and more Americans are turning toward preserving US routes. BTW very interesting treatise about your proposed route numbering system; I once worked out a routing system for an independent California along the lines of the British routes system…