You know very well they were not so regarded at the time. What does that have to do with the status of unborn children?
Incidentally, I read somewhere recently that in my home state (Massachusetts), back in the late colonial period attempts were made to enslave the native Indians. But the attempt had to be given up: The Native Americans were just too "shiftless" and undependable, and had the bad habit of always successfully escaping. If you could manage to recapture them, they'd just run away again at the first opportunity. IOW: You really couldn't enslave the native Americans. They simply refused to play along.
Why would the unborn rate a status higher than the born?
It is in the tradition of the Goebbels model of avoiding the point. A host of techniques are put into play: changing the subject (misdirecting one’s attention to some other issue, presumably one more comfortable for your opponent); ignoring the crucial question (hopefully by the aforementioned misdirection of one’s attention); and, shifting the burden (now you must explain or defend the newly introduced issue while the original proposition gets lost in the ensuing argument). And, we may expect a number of other exercises to follow as needed: the scrambling of meanings and terms, invoking the automatic disqualifier; positing a distinction possessing no difference; claiming inherited superiority; etc, etc, etc.