Andy,
So you are using size, and physical development as a condition of personhood.
A baby's brain isn't fully developed, its eyes aren't functioning properly, its sexual organs, as you said earlier, won't be developed until puberty (although Kinsey would disagree), the babys bone's aren't fused together...hence the "soft spot." They don't have teeth, their organs are still coming forming completely....
And, of course, a newborn baby is MUCH SMALLER than a person (a distinction you seem very obsessed with)
While you will immediately dismiss this an outrageous analogy...it really has more in common with yours than you will care to admit.
A baby outside the womb, is a still developing human, many of its proper bodily functions will not be completely developed for years to come...a "fetus" is a human being at the most beginning stages of this development.
Both are stages in human development...both are HUMAN, just in different forms. Now, you can make an argument that it is appropriate to kill a human at that stage of development but not others...but to claim that it is somehow not human because it isn't developed enough yet is a lie...it is a human in it most beginning stages of development.
Whether you agree or disagree, Andy, the Pro-Choice movement is slowly losing steam...statistics show that more and more young women are pro-life or at the very least support abortion with heavy restrictions...WHY?
Most critics point to 3-D ultrasounds, showing just how HUMAN that fetus is and just how EARLY it starts to look human. They point to studies who show that the fetus feels pain at much earlier stages then ever before...they look to the increasing number of women who have HAD abortions who have come forward to talk about what a painful experience it was, and how ill-prepared they were for it emotionally, how the "abortion counselors" at the clinic were just that...people counselling them to have abortions, NOT people helping them make a CHOICE. They point to people starting to see the hypocrisy in a fetus being a baby when someone wants it...but being a blob of tissue when they don't.
For the Pro-Choice movement to survive it is going to have to deal with all of these issues...and one of them is going to be dealing with the fact that an abortion ends life...it doesn't scrape out tissue, it doesn't get rid of part of your body you don't like..it ends life.
Whether or not you want that to happen is another question entirely. But the fact is, it is a human being in its earliest stages of development...and that is where we should be starting the debate.