Well, the quote I think came from someone else earlier than Il Papa, but whatever - since I can't find it, I've got nothing to work with.
Perhaps one of these:
'Let all bear in mind that a society is judged not so much by the standards attained by its more affluent and privileged members as by the quality of life which it is able to assure for its weakest members.'
-- H.E. Javier Perez de Cuellar
'The moral test of a government is how it treats those who are at the dawn of life, the children; those who are in the twilight of life, the aged; and those who are in the shadow of life, the sick and the needy, and the handicapped.'
-- Hubert Humphrey
As far as saying it is a "stretch" to include the unborn as members of society, consider this: we have an entire field of medical study for them, therapies, educational material (what to do and not to do, music to play to them, how to help them learn your voice, etc.); a section of the American Industry that depends on them.
All of which is a subsection of the field of woman's health.
And unlike animals (which have for themselves a portion of the aforementioned American Industry) they are genetically human, a member of our genus and species.
Of course, I have long defined humanity as more than a piece of dna, my preference is to define 'humanity' by intellectual capabilities and self-awareness (and the brain does not develop to this level until well into the second trimester, it's almost the third trimester until the necessary amount of brain matter is present, though substantial development of neural connections is still required at that point). By the definition of humanity you give every cell in the human body is 'human'.
I don't consider abortion an option for the poorer classes - contraception is less expensive, and most of the time does not involve the death of a fetus.
Contraception is an infinitely better course of action, you will get no arguments from me on that point. Many studies (including one I reference earlier, I believe in this thread) also demonstrate that it is the best means to decrease abortions; abortions result from unwanted pregnancies, it is of course better to ensure that these pregnancies never occur in the first place.
Of course, I don't know why you don't just advocate the elimination of the poor altogether - since you've ascribed to them a lack of self-control over their sexuality and reproduction, I don't know why you don't advocate the same for them that others do for street animals... "Help control the pet population - have your pets spayed or neutered." GreekisBobBarker.
I do advocate the elimination of the poor altogether, not by some genocidal cleansing though, I advocate the elimination of the class by giving them every opportunity to rise above their social standing. One of these means is by providing them every option possible to not be burdened by unwanted pregnancies at a young age. Contraception should be strongly encouraged, but if it is not used or if it fails we should not condemn these people to a life of poverty and hardship (which is often the case if a young unmarried woman does have an unwanted child), we should give them options so that they can overcome this mistake and still have a chance at becomming productve members of society. Young women having unwanted children then relying on the state for support in the form of welfare benifits noone, least of all the young woman in question, but removing impediments from these people improving their lives and becoming productive members of society does not merely benifit them, it benifits all of us by improving our economy and reducing the need of the government to provide.
Are my suggestions going to help everyone? No, there are many other factors that bring about poverty, but if we can help rise a few out of poverty we will also have more resources to help those poor who are not so easily aided.