This is how Jesus the Messiah was born. His mother, Mary, was engaged to be married to Joseph. But before the marriage took place, while she was still a virgin, she became pregnant through the power of the Holy Spirit.
Joseph, her fiancé, was a good man and did not want to disgrace her publicly, so he decided to break the engagement quietly.
References for Matthew 1:19
As he considered this, an angel of the Lord appeared to him in a dream. “Joseph, son of David,” the angel said, “do not be afraid to take Mary as your wife. For the child within her was conceived by the Holy Spirit.
And she will have a son, and you are to name him Jesus, for he will save his people from their sins.”
References for Matthew 1:21
All of this occurred to fulfill the Lord’s message through his prophet:
“Look! The virgin will conceive a child! She will give birth to a son, and they will call him Immanuel, which means ‘God is with us.’”
References for Matthew 1:23
When Joseph woke up, he did as the angel of the Lord commanded and took Mary as his wife.
But he did not have sexual relations with her until her son was born. And Joseph named him Jesus.