Women who used estradiol to relieve menopause symptoms had less risk of developing blood clots in their legs and lungs than they did when using conjugated equine estrogens, according to a study by the University of Washington School of Public Health. The joint study with Group Health Research Institute was led by Dr. Nicholas Smith, professor of epidemiology, and published in JAMA Internal Medicine. The study involved 384 post-menopausal women ages 30 to 79. Researchers found that women who were prescribed a generic version of estradiol experienced fewer adverse vascular events than those prescribed a patented drug marketed as Premarin, an estrogen from pregnant horses.