And Isaac prayed to YHWH for his wife, because she was barren. And YHWH granted his prayer, and Rebekah his wife conceived.
Genesis 25:21

Like Sarah before her and Rachel after her, Rebekah was barren until she conceived miraculously. It's almost like God wants us to see a pattern in the lives of the matriarchs of Israel. ;-)

{And don't miss the power of a husband's prayer in these stories either!)