“How will this be,” Mary asked the angel, “since I am a virgin?” The angel answered, “The Holy Spirit will come on you, and the power of the Most High will overshadow you. So the holy one to be born will be called the Son of God. Even Elizabeth your relative is going to have a child in her old age, and she who was said to be unable to conceive is in her sixth month. For no word from God will ever fail.” “I am the Lord’s servant,” Mary answered. “May your word to me be fulfilled.” Then the angel left her.
Luke 1:34-38 NIV