Question: While Jesus was in the womb of His mother, who was sustaining all of creation?
Answer: Jesus, of course. He is God, One with the Father, unchangeable, eternal, and could never cease to be God, the Creator and sustainer of all (Jn:1:3All things were made by him; and without him was not any thing made that was made.
See All... [1]; Col:1:17And he is before all things, and by him all things consist.
See All... [2]; Heb:1:2Hath in these last days spoken unto us by his Son, whom he hath appointed heir of all things, by whom also he made the worlds;
See All... [3], etc.). He is “the same yesterday, and to day, and for ever” (Heb:13:8Jesus Christ the same yesterday, and to day, and for ever.
See All... [4]). This is a great mystery beyond human comprehension.
So as a fetus in Mary’s womb, Jesus was still the infinite God. No wonder Paul wrote, “And without controversy great is the mystery of godliness: God was manifest in the flesh, justified in the Spirit, seen of angels, preached unto the Gentiles, believed on in the world, received up into glory” (1 Tm 3:16). We don’t understand it, but we know it is true. There is no other way to account for creation and redemption.
Links:
[1] https://www.thebereancall.org/bible/1/JHN/1/3#v3
[2] https://www.thebereancall.org/bible/1/COL/1/17#v17
[3] https://www.thebereancall.org/bible/1/HEB/1/2#v2
[4] https://www.thebereancall.org/bible/1/HEB/13/8#v8