Objectives: To review the contribution of the Nurses' Health Study (NHS) to our understanding of the complex relationship between exogenous hormones and health outcomes in women.
Methods: We performed a narrative review of the publications of the NHS and NHS II from 1976 to 2016.
Results: Oral contraceptive and postmenopausal hormone use were studied in relation to major health outcomes, including cardiovascular disease and cancer. Current or recent oral contraceptive use is associated with a higher risk of cardiovascular disease (mainly among smokers), melanoma, and breast cancer, and a lower risk of colorectal and ovarian cancer. Although hormone therapy is not indicated primarily for chronic disease prevention, findings from the NHS and a recent analysis of the Women's Health Initiative indicate that younger women who are closer to menopause onset have a more favorable risk-benefit profile than do older women from use of hormone therapy for relief of vasomotor symptoms.
Conclusions: With updated information on hormone use, lifestyle factors, and other variables, the NHS and NHS II continue to contribute to our understanding of the complex relationship between exogenous hormones and health outcomes in women.