Women who use hormonal contraception are more likely to become depressed, a large Danish prospective cohort study has found. The cohort comprised all adolescents and women aged between 15 and 34 who were resident in Denmark and without a previous history of depression, antidepressant use, other major psychiatric diagnosis, cancer, venous thrombosis or infertility treatment. Data were obtained from national registers of dispensed prescriptions and secondary care psychiatric diagnoses.