Incidence and risk factors for genital Chlamydia trachomatis infection: a 4-year prospective cohort study.

Background: Few long-term studies reporting incidence and behavioral data for Chlamydia trachomatis (CT) infection in the general population have been published. Such studies are important to understand risk factors associated with infection and to develop screening recommendations.

Methods: A fixed prospective 4-year cohort study of 898 sexually active Norwegian women, aged 16 to 23 years at study start, was conducted to assess incidence, repeat infection, and risk factors associated with genital CT infection.