Nicholas Windsor offers an excellent summary of the pro-life position, particularly with regard to the continuing moral urgency to acknowledge and address the horror of abortion (available here, as well):

There are consciences in Europe, it must be stressed, that glow white-hot for justice and strive continuously for this darkest fact of our public life to appear in public debate as clearly as it does across the Atlantic in the United States. For most of our contemporaries, however, this is a matter that impinges little. The effectiveness of determined campaigns of propaganda at the outset to harden consciences, and gradually to enforce a conformism that fears to question what is said to be a settled issue, has worked wonderfully well.
And this enforcement of a new status quo succeeds so well due, surely, to benefits enjoyed as a result—benefits of an order that make acceptable even the killing of innocents, by their protectors, on a scale that freezes the imagination. How much then must depend on its remaining so, remaining beyond question? This is the nub of that ideological word choice. So much else can be chosen in a given life if the option to dispose of unwanted children is dependably available. So many intoxicating freedoms are newly established, if only abortion is never again denied to women and to men.

Windsor notes that, beyond the direct cost to the women who abort their children, is the cost to a society as it tries to “value its own distinctive culture, when it has placed this fearful act at its center” — namely “the wish not to be bound by a pregnancy unless it is fully and freely chosen and which, outside of that parameter, is declared, by fiat, to be null and void.”
The travesty of abortion infects Western culture much more thoroughly than as a discrete issue on a slate of controversies and disagreements. It goes right to questions of what is right and who we are as spiritual and corporeal beings.