Actually, the term is medical in nature and in no way is meant to dehumanize a child in the womb. My wife is a NICU nurse, has been for over 40 years, and she and her co-workers use the term, among others, regularly. Trust me, you will rarely if ever find a NICU nurse who believes in abortion, because they know the life within each mother is precious and valuable.
The term refers to a child not yet viable outside the womb, and applies to anyone between eight and 30 weeks from birth. Before eight weeks, the child is an "embryo" by medical terminology, and after 30 weeks is an in utero infant. Though viability has been pushed all the way back to as little as 24 weeks, the term remains useful for discussion of patient condition, because obviously these wonderful nurses and doctors who protect and defend life both before and after the womb, regardless of when the "after" comes about, would prefer a child remain in utero full term, and they do everything to fight for that child's survivability in the womb.
By the same token, if mother or baby are in distress, physically ill, even biologically unmatched and therefore "battling" each others' bodies, baby must come out, and after that, my wife, her co-workers, the doctors and other medical staff fight equally hard to see to it the child survives.
Yes, they call it a "fetus" before 30 weeks, but that has nothing to do with "dehumanizing" the child whatsoever. It refers to the child's ability to survive either where he or she is, or where he or she might need to be -- i.e., in a clean, safe environment outside the mother's body -- in order to survive.