Women between the ages of 18-45 initiating long-acting progestin contraception will be enrolled at a routine office visit at the family planning clinics of each institution. Enrollment will begin in April 2016 and will stop after 6 months to allow for longitudinal follow-up and analyses. For this pilot study, a total of 30 long-acting progestin contraceptive initiators with 10 subjects in each method group (DMPA, LNG IUD, ESI) and 5 age-matched, controls seeking tubal sterilization will be selected for longitudinal STI screening and vaginal sampling for microbiome analysis.