The fetus, in many cases, dies just as a human adult or child would: It bleeds to death as it is torn from limb from limb. The fetus can be alive at the beginning of the dismemberment process and can survive for a time while its limbs are being torn off.
Stenberg v. Carhart, 530 U. S. 914 (28 June 2000) (detailing what he deemed a constitutionally protected alternative to partial-birth abortion).