A cervical ripening balloon (often called a Foley balloon or Cook balloon) is a medical device used to help prepare the cervix for labor induction when it is still firm, closed, or not ready for contractions. What is it? It’s a thin catheter with one or two small balloons on the end. When placed through the cervix and gently inflated with sterile saline, the balloon(s) apply steady pressure — encouraging the cervix to soften, thin (efface), and open (dilate) naturally. When is it used? For labor