Long-term experience with Norplant implants in international clinical trials.

Norplant subdermal implants containing levonorgestrel were used for contraception and compared with the Copper T, Model T Cu 200, during 42 months of use in an open study in Chile, the Dominican Republic, and Finland. Among 324 women enrolled for the implant regimen, there were no pregnancies in the 1st 2.5 years, and 2 by the end of 42 months. 1st segment net and gross cumulative pregnancy rates were 0.7 and 1.2/100 respectively, at 3.5 years. Cumulative pregnancy rates for the T Cu 200 group were 2.9, net and 3.5/100, gross at 42 months. More than 1/2 of the implant acceptors, 51.6/100 were continuing use at 3.5 years, somewhat above the continuation rate of the T Cu acceptors, 43.5/100, but not significantly so.