How Effective Is the IUD?
My doctor told me that an intrauterine device (IUD) is one of the most effective types of birth control. She also mentioned that two IUDs are available. How effective are the different types of IUDs?
For Mirena®, studies have shown that about 0.2 percent of women will get pregnant in the first year of use. This is a very, very low failure rate. For ParaGard®, studies have shown that the failure rate in the first year varies from 0.6 percent to 0.8 percent -- also a very low failure rate. For Skyla™ (the smaller version of Mirena that is only good for three years but can be used in women who have never given birth), the failure rate in the first year is 0.41 percent, which is very low.
The differences in effectiveness are possibly due to the different ways in which the studies were performed, so it's probably not possible to compare the numbers directly. What is most important is that they are all extremely effective, as long as they are inserted correctly and stay in place.