Abstract: A device for retarding birth, forming a lumen for surrounding a uterine cervix, the device including an upper ring for surrounding the uterine cervix, and an anchoring mechanism for anchoring the device on the cervix. A tool for inserting a device for retarding birth, the device including a device lumen for surrounding a uterine cervix, the tool including a plurality of rods attached to two rings, forming a longitudinal tool lumen, each rod including a connector for attaching to the device for retarding birth at a distal end of the rod, and a mechanism at a proximal end of the rod, for detaching the device for retarding birth at the distal end of the rod. Related apparatus and methods are also described.