The Fourteenth Amendment grants citizenship to "all persons born or naturalized" in the US.  Until it is born, the embryo would not be a citizen of the United States.

Thus under the proposed Colorado amendment (which could not overrule the Federal Constitution) an embryo would be a human being but not a citizen.  Not having obtained a visa to enter the United States, it would be an illegal alien and subject to deportation to (where?).  Query:  would its mother be guilty of knowingly harboring an alien?

Seriously, though, this amendment, if passed, would raise truly troubling legal questions.  For example, would the embryo, being considered a human being under state law, qualify as a "person"  (albeit not a citizen) within the meaning of the US Constitution?  Can a state by its laws define what the word "persons" means in the Federal Constitution?  If so, it would be entitled, among other things, to be counted in the census and to be represented in Congress.

These people are nuts.