In this study, researchers want to find out more about how the Etonogestrel (ENG) contraceptive implant device (also known as Nexplanon) changes people's periods. Study subjects will self select into an exposure group- starting combined hormonal contraceptive pills (COC) on the same day as Nexplanon placement or a "delayed initiation" of COC when/if bleeding concerns develop. Patients will be followed for 12 months.