“And her days were fulfilled,” the text says, “that she should give birth, and there were twins in her womb.” This statement, that is, “her days were fulfilled that she should give birth,” is almost never written except of holy women. For this is said of this Rebekah and of Elizabeth the mother of John51 and of Mary the mother of our Lord Jesus Christ. Whence a birth of this kind seems to me to show something extraordinary and beyond other human beings. The fulfillment of the days seems to indicate the birth of perfect offspring.
[AD 253] Origen of Alexandria on Genesis 25:24