Duration of use of copper releasing IUDs and the incidence of copper wire breakage.

The incidence of copper wire breakage for IUDs (Multiloads) using 0.3 and 0.4 mm diameter copper wire was evaluated by examining 969 devices that had been removed for various reasons. The IUDs were examined by light microscopy to determine the integrity of the copper wire. As expected, the incidence of breakage increased with increasing duration of IUD use. The cumulative breakage rate (life table) was significantly lower (p less than 0.05) for the Multiload 375 that used 0.4 mm diameter wire, compared to the Multiload 250 that used 0.3 mm diameter wire. The cumulative rates were 5.4 per 100 IUDs after 3 years for the Multiload 250, and 3.8 per 100 IUDs after 5 years for the Multiload 375. In only 1 (0.1%) of the 969 Multiloads examined, the breakage of the copper wire was sufficiently extensive to adversely affect the user's risk of pregnancy.