Monolithic intravaginal rings comprising progesterone and methods to manufacture and uses thereof

monolithic intravaginal ring comprising (a) progesterone in a concentration of 15% to 30% by total weight of the ring; (B) polysiloxane elastomer in a concentration of 55% to 90% by total weight of the ring; and (c) a pharmaceutically acceptable or glycerol ester of a fatty acid in a concentration of 0.1% to 10% by total weight of the hydrocarbon ring, wherein the progesterone is released from the vaginal ring at a constant speed for up to 18 days after administration to a patient.