Dictionaries record the word as it is used, with variations. If you're talking to a pregnant woman, you don't ask "How's the fetus?" (I don't, anyway.) You ask, "So, how's the baby?"
I use the word "baby" in one way; you use the word "baby" in another. But I doubt we'll have any disagreement at all over what DNA is, or what a chromosome is, or how to count to 46 (maybe little more or less, in some cases). We shouldn't have any disagreement at all in discussing X and Y chromosomes, or whether or not a human organism is genotypically male or female (from conception).
All else is semantic games. I can unequivocally state that every human organism not posing a clear and immediate threat to another's life has a natural and unassailable human right to live, without discriminating against that human on any basis, including: number of cells, time in existence, light-absorption level of the skin, presence or absence of a Y chromosome, or physical proximity to another human organism.
"Ambiguity is the devil's volleyball." -- Emo Phillips.