Assessing Weight Status in Adolescent and Young Adult Users of the Etonogestrel Contraceptive Implant

Study objective: There are inconsistent data regarding hormonal contraception and weight. Weight concerns might deter teens from using highly effective contraception such as the etonogestrel subdermal implant (ENG). There is little literature about weight gain and adolescent ENG use; most studies involve adult women. The purpose of this study was to evaluate weight/body mass index (BMI) change in adolescent and young adult ENG users compared with nonusers.

Design: Retrospective chart review of 197 ENG users and age, race, BMI, and follow-up time-matched controls.

Setting: Adolescent medicine clinic.

Participants: Individuals who had been using ENG for 6 months or more were eligible. A control group of non-ENG users who had been seen during the same period was identified to compare weight/BMI over time. Cases were matched to controls on age, BMI, and race.

Interventions and main outcome measures: Electronic medical records were reviewed for weight/BMI change and ENG side effects. The study was designed to have 80% power to detect a 2-kg weight difference between cases and controls.

Results: Participant mean age was 17 (±2) years. Mean follow-up was 24.5 (±9.3) months. Forty-three of 197 ENG users removed the implant early; 3/43 (6.3%) patients cited weight gain as the primary reason for removal. Mean weight change for ENG users was +3.6 (±7.8) kg vs +3.1 (±5.9) kg for controls (P = .43); mean BMI change was +1.3 (±2.9) in cases vs +1.0 (±2.3) in controls (P = .204). Overall regression analyses showed no group differences among cases and controls.

Conclusion: Long-term ENG use did not lead to significant weight gain in this sample of adolescent and young adult women. This study supports the statement that ENGs are an effective and weight-neutral option.