Sexual behaviour in Britain: why sexually transmitted infections are common.

Sexually transmitted infections (STIs) cause considerable reproductive morbidity and poor health outcomes, including pelvic inflammatory disease, infertility, ectopic pregnancy, cervical cancer, neonatal disorders and death.1 They are often associated with significant social stigma and are a source of psychological stress, with adverse impacts on individuals and their relationships. Early diagnosis and treatment of STIs, as well as targeted prevention efforts, can significantly reduce the likelihood of these complications. Population patterns of sexual behaviour are major determinants of STI and HIV transmission. In Britain, the past decade has seen substantial changes in the epidemiology of these infections.