Nurses' Health Study

Abstract

T he Nurses' Health Study was begun in 1976 with the establishment of a cohort of 120,700 women aged 30-55 and was principally designed to assess risk factors for breast cancer. Cohort members initially resided in 11 geographically dispersed states representing the Northeast (Massachusetts, Connecticut, New York, New Jersey, Pennsylvania, Maryland), Northcentral (Ohio, Michigan), the West (California) and the South (T exas, Florida); although the majority of participants still reside in the original 11 states, members of the cohort currently live in all 50 states. T hese women report on exposures and disease outcomes every two years and follow-up in the cohort has been maintained at a level of better than 90% through 1990. Qeios · Definition, February 2, 2020