How could Mary be the mother of the One who created her?

The Catholic Answers

Mary owed her being, of course, to God, but this under the aspect of His eternal Nature. Subsequent to her creation that human nature was born of her which the Son of God had assumed to Himself. She was, therefore, the mother of Christ. But Christ was one Divine Person existing in two natures, one eternal and divine; the other temporal and human. Mary necessarily gave birth to a being with one Personality and that Divine, and she is rightly called the Mother of God.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty