Why are men and women at different risks of high blood pressure?

Reasons for gender differences in blood pressure are not known but are being investigated by many scientists. It has been suggested but not proven that estrogen is responsible for the lower blood pressure in younger women, but the relationship between estrogen levels and blood pressure is complex. While numerous studies have shown that hypertension is twice as prevalent after menopause, it is unclear whether the increased risk is caused by the drop in estrogen or by other factors such as weight gain, decreased physical activity and increased alcohol intake. Adding fuel to the controversy is a study in Finland that showed women who had undergone hysterectomy had higher blood pressure than women who had not undergone hysterectomy, even when their estrogen-producing ovaries were left intact.