[hocndoc]

The embryo and fetus need less effort on the mother's part to "feed" than the infant does. Even a breast feeding mother has to pick up and postition the child (not to mention take care of the diapers).
And, by your definition, none of the people dependent on IV's and feeding tubes are persons.

In the case of the infant and small child (and all the people on IV's and feeding tubes), someone else can kill them by neglect: just don't feed them, they'll die. In the case of and elective abortion on the prenatal human, someone must purposefully and intentionally act to kill.

[Semper]

And, by your definition, none of the people dependent on IV's and feeding tubes are persons.

Completely wrong. My definition of a human person is a being with a human consciousness. People dependent on IV's and feeding tubes in the most part have consciousness and are aware of their existence. Human beings have no awareness or memory of pre-conception life or zygot life or fetal life. There is one clear event which initiates the beginning of human consciousness and that event is birth.

There may be evidence of brain activity before birth - there is brain activity in all manner of lower life forms - but the beginning of human consciousness can only be identified after being born into this human environment.