So, not getting bogged down with the value we place on specific instances of life, like human foetuses:
The value of life in general to me is above all that as far as we know at this point it exists only on one small blue-green speck of dust in one corner of one galaxy. A vast array of complex forms which, even now, we're still discovering. Evolving into ever more complex forms, the most complex of which have reached a point of self-awareness such that they can contemplate their own nature and origins. The whole process powered by a ball of hydrogen fusing into helium eight light minutes away.
In poetry and prose, the greatest but most succinct contemplation of the wonder of the natural world and of human life that springs to my mind is the one which contains within it the irony of Hamlet contemplating his own depression and disillusionment with it all:
Shakespeare wrote:I have of late, but wherefore I know not, lost all my mirth, forgone all custom of exercises; and indeed, it goes so heavily with my disposition that this goodly frame, the earth, seems to me a sterile promontory; this most excellent canopy, the air, look you, this brave o’erhanging firmament, this majestical roof fretted with golden fire, why, it appears no other thing to me than a foul and pestilent congregation of vapours. What a piece of work is man! How noble in reason! how infinite in faculties! in form and moving, how express and admirable! in action how like an angel! in apprehension, how like a god! the beauty of the world! the paragon of animals! And yet, to me, what is this quintessence of dust?
I could go on. But no matter now long I went on, abortion would remain irrelevant. If I could pick the most relevant single theme it might be the tragedy of the
Holocene extinction which we're currently going through, and, incidentally, to which global access to human birth control and the defence of women's rights over their own fertility and family planning
is relevant.