Nexplanon Use in Women Primarily Choosing a Combined Oral Contraceptive

This study will be conducted at three sites across the United States: University of California, Davis, University of Colorado and University of Pennsylvania. Investigators will recruit women currently using COCs or intending to initiate COCs for pregnancy prevention. Each site will recruit approximately 40 women for a total of 120 subjects. Visit 1: Informed consent will be obtained. As part of informed consent, subjects will be educated that there is little data available on the adverse effects of combined COC and ENG implant use. The consent form will include a standardized description of the side effects and bleeding profile of COCs and the implant. Subjects will also need to review the package label information for Nexplanon and sign the FDA-required Nexplanon consent. After obtaining informed consent, subjects will be screened for entry criteria. Medical history will be obtained. A urine pregnancy test will be performed. Eligible subjects will have a Nexplanon contraceptive implant placed. A diary will be dispensed for the subject to document daily bleeding, COC use and adverse events. Follow-up: Follow up contact will be at approximately 4, 12, 26 and 39 weeks with the exit visit scheduled at 52 weeks. At each follow up contact, the diary will be reviewed. Adverse events will be determined by inquiry and diary review. The subject will inform the study staff if she is using her COC and if she wants to continue use of her COC and ENG implant. The ENG implant will be removed upon request at any time during the study. Study participation will be complete after the 52 week (\~ 12 month) exit visit. No blood draws will occur during this study. A diary will be used but no surveys will be used. Data to be collected by study staff include demographics, past medical and gynecologic history, prior and current contraceptive use. Because women are being enrolled who are already currently using COCs or who plan to start COCs, the COC is not a study drug. The study intervention (study drug) is the contraceptive implant. The systemic hormone exposure with a contraceptive implant is minimal relative to a COC. The investigators do not expect any increase in side effects by adding a contraceptive implant to COC users. Of note, the primary risk with COC use is related to the estrogen which can increase the risk of venous thromboembolic disease. The implant has no estrogen. All products being used in the study are FDA-approved for contraception.