OBJECTIVES: To describe changes in systolic blood pressure (SBP), diastolic blood pressure (DBP), and body mass index (BMI) associated with initiation and continued use of combined oral contraceptives (COCs) in healthy adolescents. STUDY DESIGN: This observational, matched cohort study was conducted in 2 large health systems. Utilizing claims and electronic medical records, we identified adolescents 14-17.9 years of age initiating medium-dose COCs (containing 30 or 35 (mug of ethinyl estradiol or equivalent and a progestin) between July 1, 2007 and December 31, 2009 with a baseline and at least 1 follow-up blood pressure (BP) and BMI. COC-users were matched 1:2 by age, race/ethnicity, and site to controls (COC-nonusers). All BPs and BMIs recorded during outpatient visits starting 1 month prior to COC initiation (index date for controls), through December 31, 2010 were collected. Mixed model linear regression with random intercepts and slopes were then used to estimate changes in SBP, DBP, and BMI over time. RESULTS: The 510 adolescent COC-users and 912 controls did not differ significantly by age, race/ethnicity, insurance, and baseline SBP, DBP, or BMI. After adjusting for baseline values, over a median of 18 months follow-up, COC-users had an decrease in SBP of 0.07 mm Hg/mo, and controls had an increase of 0.02 mm Hg/mo (P = .65). Similarly, DBP decreased by 0.007 mm Hg/mo in COC-users vs 0.006 mm Hg/mo in controls (P = .99). BMI increased by 0.04 (kg/m(2))/mo in COC-users vs 0.025 (kg/m(2))/mo in controls (P = .09). CONCLUSIONS: These data should provide reassurance to patients and providers regarding the lack of significant associations between COC-use and BMI or BP changes in adolescents.