I think abortion is "okay" up until the gestational age at which the fetus/baby would survive if delivered prematurely.
Babies can survive after 24-25 weeks of gestation. Normal gestation is 38-42 weeks. By the best numbers I can find in short time I'm going to put into this, only 1.4% of all abortions in the US occur after 21 weeks.
Late term (post 21 weeks) abortions should be illegal, IMHO, except in cases where the fetus/baby would not survive (severe illness) or it's delivery would endanger the life of the mother. Why? If the only difference between fetus and baby is a centimeter of the mother's tissue, then I'd have to call that a viable human life. But whatever, it's just my opinion and in reality, this category only comprises a small percentage of abortions...
BTW, most of this comes from Wikipedia, so feel free to double check or provide better data...
Description of mid and late-term abortion procedure:
The procedure consists of pulling the fetus out of the womb with forceps, delivering the fetus entirely except for the head. Scissors are used to open the skull, and the brain is suctioned out to ensure death. The fetus is then removed.
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Why do you need to "ensure death" for something that was not alive?