The women had home interviews, baseline examinations, follow-up of menstrual cycles, and a six-month self-administered questionnaire. Risk factors studied included behavioral factors, glucose and insulin, obesity, exercise, cigarette smoking, nutrition, lipoproteins, blood pressure, and hormones. Surgical menopause and the use of exogenous hormones were also studied. Although not part of the original protocol, measurements of fat distribution, coagulation factors, apoproteins, sodium-lithium counter-transport, and sodium-hydrogen exchange in platelets were added.