Chelsea Polis joined the Guttmacher Institute as a Senior Research Scientist in 2014. Trained in epidemiological methods, Dr. Polis has designed and implemented randomized clinical trials, analyzed observational data, and conducted several systematic reviews and meta-analyses. Her research has included work on contraceptive safety, effectiveness, choice, acceptability and accessibility, and she has particular expertise on the epidemiological associations between hormonal contraceptive methods and various HIV-related risks. She has conducted research on abortion-related issues, multipurpose prevention technologies, measurement of infertility, correlates and impacts of perceived infertility, and other subjects in sexual and reproductive health. Dr. Polis earned a BA in medical anthropology from Brown University, and completed her PhD and postdoctoral fellowship at the Johns Hopkins Bloomberg School of Public Health, where she focused on reproductive health epidemiology. Prior to joining the Guttmacher Institute, she served as Senior Epidemiological Advisor to the Office of Population and Reproductive Health at the United States Agency for International Development. Her ongoing collaborations with the World Health Organization (WHO) and the Centers for Disease Control and Prevention contribute to efforts toward updating global contraceptive guidance in the WHO’s Medical Eligibility Criteria for Contraceptive Use. She also holds an Associate appointment in the Department of Epidemiology at the Johns Hopkins Bloomberg School of Public Health.