This review aimed to assess how effective contraceptive implants were at preventing pregnancy and how acceptable women found them compared to other methods of contraception.

All the trials identified compared different types of contraceptive implant. No trials were found that compared implants to other contraceptive methods. All the implants were highly effective methods of contraception in the selected women. The majority of women using contraceptive implants chose to continue with the method long term, over 80% of women were still using their implant at two years. Women in developed country studies were less likely to continue with these methods when compared to women in developing country studies. The most common reported side -effect was of irregular vaginal bleeding. Bleeding with all implants became less frequent with time. Removal was quicker for Implanon and Jadelle than for Norplant. Insertion problems were rare with any of the implants. Problems at removal were uncommon but were significantly more likely to occur in Norplant users than Implanon users.

Authors' conclusions: 

Implanon, Norplant and Jadelle are highly effective contraceptive methods. No significant differences were found in contraceptive effectiveness or continuation. The most common side-effect with all implants was unpredictable vaginal bleeding. Time taken for removal of Implanon and Jadelle was less than that for Norplant.
Although this systematic review was unable to provide a definitive answer on relative effectiveness, tolerability and acceptability of contraceptive implants in comparison to other contraceptive methods, it has raised issues around the conduct of contraceptive research.

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Background: 

Implantable methods of contraception offer long-acting reversible contraception. Their uptake rate in comparison to other contraceptive methods, particularly in developed countries, has historically been low.

Objectives: 

To assess the contraceptive effectiveness, tolerability and acceptability of subdermal implants in comparison to other reversible contraceptive methods.

Search strategy: 

Literature were identified through database searches, reference lists and individuals/organisations working in the contraceptive field.

Selection criteria: 

All randomised and controlled trials comparing subdermal implants with other forms of reversible contraceptives and reporting on pre-determined outcomes in women of reproductive years. Primary outcomes were pregnancy and continuation.

Data collection and analysis: 

Quality assessment of studies and data extraction were completed independently by two reviewers. A quality checklist was designed to identify general methodological and contraceptive specific factors. Study authors and pharmaceutical companies were contacted to provide additional data.
Data were collected on pregnancy rates, continuation, side effects and adverse events.

Main results: 

All nine identified trials compared different types of contraceptive implant. Eight, involving 1578 women, compared Implanon with Norplant , and one, involving 1198 women, compared Jadelle with Norplant. There was no difference between Implanon and Norplant for contraceptive effectiveness rates or continuation over 4 years. Both were highly effective methods of contraception with no pregnancies occurring in any of the trials during 26,972 and 28,108 women months of follow up respectively. The most common side-effect with Implanon and Norplant was changes in bleeding pattern. The pattern with Implanon was initially more variable, bleeding with both implants became less frequent with duration of use. After two years use the amenorrhoea rate was significantly higher with Implanon. The trials reported no significant difference in hormonal side-effects or adverse events. Implanon was significantly quicker to insert and remove than Norplant.
There was no difference in contraceptive effectiveness and in continuation rates between Jadelle and Norplant. Jadelle was significantly quicker to remove than Norplant.

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