I have had this very thought for many years now.
A close friend had an aneurysm years back, but who was revived (though never resuscitated). In order to remove him from life support, the hospital was required by law to do an EEG to try to detect alpha waves (and thus consciousness, by definition). The test came back negative, and his family helped him to pass on.
I have wondered since what the feasibility would be of running such a test on a foetus to determine the presence of consciousness. This would seem a logical and scientific way to remove the philosophy/religion from the debate altogether and allow everyone to move on.