Source: FHI clinical trials, 1985-1989.
As seen on the previous slide, failure rates vary widely among
different contraceptive methods. There is also variability among
different types of the same method. For example, as this slide
shows, copper IUDs being distributed at this time are very effective.
However, the TCu 380A has shown the lowest pregnancy rate of
any copper IUD in comparative trials. In FHI clinical trials,
failure rates for any of these five IUDs were less than 4 percent
after one year of use. However, failure rates among the average
population may be slightly higher.
Note that each IUD has a recommended lifespan. This means that
the IUD is effective for up to a specific number of years from
the date of insertion. For example, if a woman had a TCu 380A
inserted today, she would not need to have it replaced or removed
for 12 years.