In one embodiment, the present invention provides an intrauterine device (IUD) comprising an oval shape, wherein the device comprises a core of magnetic material, an inert material or copper coating the core, wherein the coating comprises a pharmaceutical agent, copper or a combination thereof. Another embodiment provides a method to suppress estrus in a subject comprising inserting an intrauterine device (IUD) comprising an oval shape, wherein the device comprises a core of magnetic material and an inert material or copper coating the core.
