[Contraception and obesity]

Effectiveness of the etonogestrel subdermal implant in users with overweight and obesity: a systematic literature review

BACKGROUND

The etonogestrel (ENG) subdermal implant is considered a well-tolerated and effective contraception option to avoid unintended pregnancies. However, it is unclear whether being affected by overweight or obesity diminishes the effectiveness of the implant.

OBJECTIVES

To systematically assess the published evidence on implant contraceptive effectiveness in women with overweight or obesity, and in women who underwent bariatric surgery.

SEARCH STRATEGY

A systematic search of MEDLINE and Embase for publications reporting implant effectiveness since 2011.

SELECTION CRITERIA

Primary publications of randomised and non-randomised trials, observational studies and case reports were included.

DATA COLLECTION AND ANALYSIS

Two independent reviewers identified the Pearl Index, qualitative descriptions of contraceptive failure, implant exposure and potential bias, and assessed overall quality of evidence.

MAIN RESULTS

We found 12 publications meeting our criteria, consisting of nine observational studies and three case reports. Excluding case reports, the publications reported Pearl Indices from 0.0/100 women-years (WY) to 0.23/100WY for women with overweight and obesity, respectively. No studies met the eligibility criteria for the post-bariatric surgery population.

CONCLUSIONS

Observed implant effectiveness in women with overweight and obesity falls within the range of published data across all weight groups (0.0-1.4/100 WY) and does not suggest a reduced effectiveness associated with higher body mass index. Large, well-controlled studies designed to specifically assess the effectiveness of the ENG implant with respect to user weight, particularly in women following bariatric surgery, are warranted.