Ambrose of Milan

And Rebecca conceived, and by her patience she untied the knot of sterility. But let us consider what the prophetic and apostolic soul gives birth to and how it gives birth. She went, it says, to inquire of the Lord (Gen. XXV, 22), because the infants in her womb were rejoicing. And she received this answer: Two nations are in your womb (Ibid., 23); for she presumes nothing of her own accord, but in all things she seeks the highest God as the ruler of her plans. …

On Isaac and the Soul ↗

Jerome

And Rebecca his wife conceived, and the sons within her were moved. Concerning this movement, the Seventy Interpreters rendered it as ἐσκίρτων, which means they were playing or kicking; which Aquila translated as they were breaking in the womb. But Symmachus rendered it as διέπλεον, which means they were carried on the surface like a ship.

Hebrew Questions on Genesis ↗

Bede

Thus Isaac, the son of the promise, who as a figure of our Redeemer became obedient to his father even unto death, was born of parents who were old. He had a mother who had long been barren. Thus Jacob, the patriarch Joseph, Samson, [who was] the bravest of the chieftains, and Samuel, [who was] the most distinguished of the prophets, [all] had as their progenitors [mothers who were] for a long time barren in body but always fruitful in virtues. …

Homilies on the Gospels 2.19 ↗