Risk of early etonogestrel and levonorgestrel implant discontinuation in adolescents and adults.

Background: Etonogestrel and levonorgestrel implants are effective for 3 and 5 years of contraception, respectively. The removal of contraceptive implants before the due date, also known as implant early discontinuation, contributes to unplanned pregnancies, which can lead to unfavourable reproductive health outcomes, especially in adolescents. We aimed to assess the magnitude of early implant discontinuation among those who initiated the method at our hospital, and to compare this rate between adolescents and adults.

Methods: This retrospective cohort study reviewed the medical records of participants who initiated contraceptive implants from January 2014 to December 2019 at King Chulalongkorn Memorial Hospital. Early discontinuation was defined as the removal of implants prior to the due date. Cox proportional hazard regression analysis was performed to identify factors associated with early discontinuation.

Results: Our analysis included 1,435 participants, 409 of whom were adolescents. Levonorgestrel implants were used by 53.3% of the participants(68.7% and 47.1% of adolescents and adults, respectively); the remainder used etonogestrel implants. The total early discontinuation rate was 19.3%, which was comparable between the two implant types. The most common reason for discontinuation was intolerance of side effects, with abnormal bleeding being the most frequent. Adolescents were less likely to discontinue implants early (HR 0.72, 95% CI = 0.55-0.95). Factors significantly associated with decreased early discontinuation were: free-of-charge implants (HR 0.75, 95% CI = 0.58-0.95), continuous users of implants (HR 0.56, 95% CI = 0.36-0.86), postpartum status during implant initiation (HR 0.77, 95% CI = 0.60-0.98), and participants with children (HR 0.77, 95% CI = 0.60-0.99).

Conclusion: Compared with adults, adolescents were less likely to discontinue contraceptive implants before the due date. Participants who received free implants, continuous users who had previously used implants, postpartum insertion, and having children were associated with less early discontinuation. Our findings supports continued government funding for free implants in Thailand.