Long-term follow-up of women treated with Norplant implants

This report describes the long-term follow-up of 376 women who received NORPLANT implants in the period October 1974 through May 1979. One-hundred-and-ten subjects received replacement implants after variable lengths of use of the first set. The average levonorgestrel plasma levels declined steadily through eight years of use of NORPLANT capsules (r = -.937). Values were 0.35 ng/ml, 0.29 ng/ml and 0.22 ng/ml at treatment years 1, 5 and 8, respectively. Levonorgestrel plasma levels after replacement with a second set of implants were similar to those observed after the first insertion, either when placed in the same site as the first set or in a different area. Nineteen pregnancies occurred during 18,530 woman-months of use of the first set of implants, eleven of them during years 6 through 8 of treatment. The Pearl Index for the first 5 years of NORPLANT implants use was 0.63. No pregnancy has occurred in 4194 woman-months observed during treatment with a second set of capsules. Fifty-six women (14.9%) out of 376 acceptors of the first implant and 10 (9.1%) out of 110 acceptors of the replacement implants were terminated for other medical reasons, mainly bleeding problems and side effects commonly associated with hormonal contraception. Two women died while using NORPLANT implants, one of a cardiac arrest after surgery for a gallbladder disease and one because of endocranial hypertension originating from the rupture of an aneurism of the median cerebral artery. The bleeding pattern observed in the three months after NORPLANT capsules replacement was similar to that observed in the 90 days before replacement and different from that experienced by the same women in the first 90 days of implant use. This finding can be interpreted as an indicator of adaptive changes experienced by the target organs during long-term continuous administration of levonorgestrel. The prompt recovery of fertility after removal of NORPLANT implants suggests that these changes are reversible.