The copper IUD (tradename is Paraguard) has a plastic t-shaped frame with copper wire coiled around it. The copper IUD releases copper ions which is toxic to sperm movement and egg fertilization. It also produces an inflammatory reaction which interferes with implantation. It is 99% effective at preventing pregnancy and lasts for ten years. This really is the best bang for your health care dollars. This device costs about $1000 and is covered by most insurances. If you use it for ten years- this comes out to about $8 per month for birth control. Considering that most insurances cover it at a 100%, it likely won’t cost you anything. However, there are some potential undesired side effects. Because the copper IUD prevents pregnancy by producing an inflammatory reaction in the uterus, many women experience more painful periods and heavier bleeding than usual. For some women these symptoms do improve over time, but this can take up to a year to notice improvement. However, many do not notice any improvement over time, and for those women the only option is to remove the IUD.
The progestin-based IUD (tradenames include Mirena and Liletta, among others) also has a plastic t-shaped frame that contains a progestin hormone. Progestin is similar to the hormone progesterone which our bodies make naturally. This type of IUD will last 5 years. The progestin in the IUD prevents pregnancy by thickening cervical mucous which affects sperm motility and it thins the lining of the uterus preventing implantation. Because the progestin acts locally in the uterus, many side effects that women experience with oral birth control like nausea, breast tenderness and mood changes are not experienced with the progestin- based IUD. Also, it also does not affect breast milk supply if you are breastfeeding. While copper IUD’s can worsen menstrual bleeding and cramping, most women with the progestin- based IUD experience less bleeding and 20% of women never have any bleeding while the IUD is in place. Because of these non-contraceptive benefits, many women with heavy menstrual bleeding will use the progestin-based IUD just to control their bleeding. However, some women can have irregular bleeding or spotting with the progestin-based IUD.
So, this blog helps provide a basic framework about the differences between the copper and progestin-based IUD. That being said, given your individual medical history, one of the options may be more effective or appropriate for you than the other. Be sure to talk to your provider about your contraception goals, and together you can find what can work best for you.