Intrauterine Contraception (IUC) is one of the most reliable contraceptive methods, licenced for use between 3 to 10 years. The copper intrauterine device (Cu-IUD) is non-hormonal and lifetime varies between 5 – 10 years. It has a plastic core coated with copper which not only inhibits the motility of sperm and ova, but also has some effects on cervical mucous and implantation itself. It is one of the most effective methods available. The TCu380A has a cumulative pregnancy rate of just 2.2% after 12 years (2 years after the licence period).
The LNG-IUS is a plastic coil containing levonorgestrel progestogen. There are currently three strengths available in the UK. Mirena and Levosert contain 52mg of LNG and is licenced for use for 5 years (or after the age of 45years until the menopause). Jaydess contains only 13.5mg of LNG and is licenced for 3 years. Kyleena, relatively new to the market, contains 19.5mg of LNG, and like Mirena, is licenced for 5 years. LNG-IUS predominantly work by thinning the endometrium, thereby preventing implantation. They also have some effect on cervical mucous, and, in about a quarter of women, prevent ovulation.
Contraceptive rates are similar in both Cu-IUDs and LNG-IUS.