Prolonged effectiveness of Norplant® capsule implants: A 7-year study
Sivin,Irving; Mishell,Daniel R.,Jr.; Diaz,Soledad; Biswas,Arijit; Alvarez-Sanchez,Francisco; Darney,Philip; Holma,Pentti; Wan,Livia; Brache,Vivian; Kiriwat,Orawan; Abdalla,Kamal; Campodonico,Italo; Pasquale,Samuel; Pavez,Margarita; Schechter,Janet
Contraception 61(3): 187-194
Publication date: 2000
Soft tubing Norplant® contraceptive implants were studied in 1210 women for 7 years to measure the duration of effectiveness and the magnitude of the pregnancy rates over that time. Mean age at enrollment was 27.4 years. Of the enrollees, 42% were US residents. One-sixth (16.1%) weighed =70 kg at the time of implant placement. At the end of 5 years, the cumulative pregnancy rate was 1.1/100; at the end of 7 years, it was 1.9/100. No pregnancies occurred to any of the 400 women who enrolled in the study at age =30 years and who weighed <100 kg. Among women aged 18-33 years, the 7-year Norplant pregnancy rates are comparable to the median pregnancy rates of tubal sterilization methods for women of the same age and duration of use. For women aged =34 years, without regard to weight at admission, the 7-year effectiveness of soft tubing Norplant equals or surpasses that of tubal sterilization. For continuing implant users, annual pregnancy rates <1.0/100 in years 6 and 7, together with low cumulative pregnancy rates, testify that Norplant capsule implants remain highly effective for 7 years.