Johns Hopkins Bloomberg School of Public Health: The INFO Project

Regulatory agencies generally recommend a five-year limit on use of Norplant implants applicable to all women. Studies of Norplant implants have found, however, that a woman’s weight and age affects the duration of contraceptive effectiveness (23, 50). Based on this evidence WHO now recommends that the time between insertion and removal of the implants can depend upon the user’s weight. The Expert Working Group did not make any references to a woman’s age in the recommendation because younger women tend to have higher pregnancy rates than older women regardless of the contraceptive method used, due to their higher fecundity.

The Expert Working Group advises that:

• Women who weigh less than 70 kg (154 pounds) at insertion of their Norplant implants and who continue to weigh less than 70 kg can leave the implants in place for up to seven years.



• Women who weigh between 70 and 79 kg (154 and 174 pounds) at insertion should be advised that their Norplant implants will be less effective after five years of use if they still weigh between 70 and 79 kg at that time (23, 50). The effectiveness of Norplant implants in women in this weight range in years six and seven of use is reduced but still greater than that of most other contraceptive methods, including injectables, OCs, and condoms (all as typically used) (61). After five years the woman, with counseling from her health care provider, can decide whether to leave the implants in place for the additional two years, to replace them with a new set of implants, or to switch to a different contraceptive method.



• All women should be counseled that, if they weigh 80 kg (176 pounds) or more at the end of four years of Norplant use, they should seriously consider having their implants replaced because of their reduced contraceptive effectiveness. The Expert Working Group reviewed evidence that women weighing 80 kg or more have an approximately 6% chance of getting pregnant in the fifth year of Norplant implant use (50). While this pregnancy rate is comparable to that of combined oral contraceptive pills as typically used, it is much higher than in earlier years of Norplant implant use.

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