Violet, I scowl in your general direction. I know you understand what I'm getting at. Damn you for making me be clearer in my wording and terminology!! Curse you! 
I brought up the fetus being human because The Guy Who Asked Questions seemed to have thought I implied a fetus isn't human. It is.
A severely premature infant cannot survive on its own period. It can't regulate body temperature, can't eat without medical assistance, has a virtually non-functioning immune system and is highly susceptible to infections, can't get oxygen on its own (due to immature lung functioning). By comparison a full-term newborn can do all of these things and is relatively independent, just change its nappies and give it a boob (or bottle if you prefer). Snuggles are ideal as well, though not mandatory, but if neglected lack of snuggling can lead to attachment issues in child and adulthood. And nappies and bottles can be changed/given by people by people other than the mother, whereas with a severely premature infant, the best place for it to thrive is the mother's womb. Indeed, depending on gestational age, the womb is the only place a fetus can survive at all.
People who are crippled are a different matter entirely. If through neonatal testing the fetus is found to have problems, it is the parents' decision to bring the baby term or to end the pregnancy. While admittedly unsavory to abort a 20+ week fetus this is one of the main reasons its done. Personally, I didn't have any genetic testing with either of my pregnancies and only had one ultrasound for each, the routine 20 week fetal development check. I would have wanted my babies if they had no kidneys, cleft palates, or had Down syndrome. Though, if the scan had shown they weren't developing parts of their brains, I think I would have strongly considered termination. Don't know, can't say for certain and this is dependent upon which portions were not developed, I think that is something one has to go through to know 100% what one would do. That's me, but I don't presume everyone to feel the same way I do about such a personal issue.
I view abortion as a woman's right to choose. Her body, her life, her offspring, her choice.
I also tie in birthing choices and options under this umbrella. I can get a bit rabid on that front and save most of my ranting about birth options for birth forums.

I brought up the fetus being human because The Guy Who Asked Questions seemed to have thought I implied a fetus isn't human. It is.
A severely premature infant cannot survive on its own period. It can't regulate body temperature, can't eat without medical assistance, has a virtually non-functioning immune system and is highly susceptible to infections, can't get oxygen on its own (due to immature lung functioning). By comparison a full-term newborn can do all of these things and is relatively independent, just change its nappies and give it a boob (or bottle if you prefer). Snuggles are ideal as well, though not mandatory, but if neglected lack of snuggling can lead to attachment issues in child and adulthood. And nappies and bottles can be changed/given by people by people other than the mother, whereas with a severely premature infant, the best place for it to thrive is the mother's womb. Indeed, depending on gestational age, the womb is the only place a fetus can survive at all.
People who are crippled are a different matter entirely. If through neonatal testing the fetus is found to have problems, it is the parents' decision to bring the baby term or to end the pregnancy. While admittedly unsavory to abort a 20+ week fetus this is one of the main reasons its done. Personally, I didn't have any genetic testing with either of my pregnancies and only had one ultrasound for each, the routine 20 week fetal development check. I would have wanted my babies if they had no kidneys, cleft palates, or had Down syndrome. Though, if the scan had shown they weren't developing parts of their brains, I think I would have strongly considered termination. Don't know, can't say for certain and this is dependent upon which portions were not developed, I think that is something one has to go through to know 100% what one would do. That's me, but I don't presume everyone to feel the same way I do about such a personal issue.
I view abortion as a woman's right to choose. Her body, her life, her offspring, her choice.
I also tie in birthing choices and options under this umbrella. I can get a bit rabid on that front and save most of my ranting about birth options for birth forums.