2 I pass over the facts that, before her birth, she was blessed while still in her mother's womb, and that, virgin-like, she was delivered to her father in a dream in a bowl of shining glass brighter than a mirror. And I say nothing of her consecration to the blessed life of virginity, a ceremony which took place when she was hardly more than ten years old, a mere babe still wrapped in swaddling clothes. For all that comes before works should be counted of grace; although, doubtless, God foreknew the future when He sanctified Jeremiah as yet unborn, when He made John to leap in his mother's womb, and when, before the foundation of the world, He set apart Paul to preach the gospel of His son.
Source: Letters (New Advent)