Etonogestrel implant use in women primarily choosing a combined oral contraceptive pill: A proof-of-concept trial.

Objective: We evaluated a novel concept of initiating the etonogestrel implant as a "back-up" method in women who desire using combined oral contraceptives (COC) but want to decrease their risk of unintended pregnancy with a more effective method.

Study Design: In this prospective cohort study, we planned to include 20 women as a proof-of-concept. We enrolled both new COC starters and continuing COC users and placed an etonogestrel implant. Participants completed daily bleeding diaries and attended follow-up visits at 1, 3, and 6 months. We assessed implant continuation through six months of study participation and side effects with dual hormonal contraceptive use.

Results: Between September and December 2016, we enrolled 10 new starters and 10 current COC users. All participants completed 1-month follow-up, and 18 (90%) subjects completed the 3- and 6-month follow-up assessments. Two current COC users had the implant removed for mood changes before 6 months. At the 6-month follow-up visit, 10 women were using both pills and implant, seven relied on the implant only, and one was using a COC only. Three new starters chose implant removal at end of study participation; one for weight gain and acne, another for mood changes, and one for decreased libido. No subjects discontinued the implant for bleeding complaints.

Conclusion: In this proof-of-concept study, women using COCs were willing to initiate the implant as a "back-up" method to improve pregnancy prevention. Most women continued the implant through 6 months and after completing study participation.

Implications: Initiating the etonogestrel implant as a "back-up" method may be an option for women who desire more effective pregnancy prevention while using combined oral contraceptive pills for its bleeding profile or non-contraceptive benefits.