In addition to increasing the inflammatory response, copper changes the levels of certain enzymes in the uterus. This alters the uterine environment so that it is unlikely that a sperm and an egg would survive to unite. This IUD is effective for up to eight years. This IUD is also T-shaped. In the stem of the T is a reservoir with 38 milligrams of progesterone.
Progesterone is a female hormone that brings on menstruation.
It also thickens cervical mucus. This thickened mucus makes it difficult for sperm to pass through the cervical opening to the uterus. The Progestasert IUD is reliable as long as there is progesterone in the reservoir. It's usually changed about once a year. This device is similar to the Progestasert IUD but contains a different hormone, levonorgestrel.