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Contraception. 2018 Jun;97(6):533-537. doi: 10.1016/j.contraception.2018.02.009. Epub 2018 Feb 26.

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

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Department of Obstetrics and Gynecology, University of California, Davis, 4860 Y Street, Suite 2500, Sacramento, CA 95817. Electronic address:
Department of Obstetrics and Gynecology, University of California, Davis, 4860 Y Street, Suite 2500, Sacramento, CA 95817.



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.


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.


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.


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.


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.



combined oral contraceptive; etonogestrel; implant; vaginal bleeding

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