God does the work through his Holy Spirit
Let us remember that moment when the angel Gabriel appeared and announced to Mary the miracle of the incarnation of the son of God in her womb. This is one of the scenes where our faith begins, God the man through the Holy Spirit in a woman.
Here we see the result of that which is impossible for men, God does it, we remember that Mary did not understand how she could be a mother if she had not yet known a man, but the angel was very specific and assured her that this was the work of the Holy Spirit. This invites us to trust in the power of God through the Holy Spirit as well as Mary.
The angel answered and said to her, The Holy Spirit will come upon you, and the power of the Most High will overshadow you. Therefore the holy one to be born will be called the Son of God.
Luke 1:35