Anything less would not be an accurate description of who Christ is.
Regards
How are "Mother of Christ" or "Mother of the second person of the Trinity" not accurate descriptions of who Christ is? When you use "Mother of God" you MUST explain that it does not include the Father and the Spirit. With "Mother of Christ" one MUST explain that Christ is God, etc. What is so special about "Mother of God" as opposed to other descriptions?