Then why do they start pulling away from the scalpal when the abortionist begins his barbarity?
Why do worms?
Trauma responses are very low-level, far below the threshold of consciousness or meaningful brain function of any type. It is why they anaesthetize even the most primitive of creatures when doing research -- to minimize a trauma response that will interfere with the research being performed. Since they are simply killing the fetus, mitigating the trauma response is apparently not a significant concern for the abortionists.
A response to physical trauma is orthogonal to consciousness or even having a real CNS to speak of, and conflating one with the other is damaging to the credibility of the arguments against abortion.