Researchers, working from centers in England, Australia and New Zealand, studied 5,692 women with an average age of 63 and who were an average of 15 years post-menopause. Randomly split into two groups, the women either took a daily hormone replacement pill or a placebo pill as part of the Women's International Study of long Duration Oestrogen after Menopause (WISDOM).

After following the women for a year, the researchers report women taking combined hormone therapy, which included estrogen and progestogen, were significantly more likely to experience major cardiovascular events (angina, heart attack or sudden coronary death) and blood clots.

"This is consistent with the early findings of the Women's Health Initiative and other trials, and supports the conclusion that combined oestrogen and progestogen therapy should not be initiated to prevent cardiovascular disease in older post-menopausal women.

"However, these results cannot necessarily be applied to younger menopausal women starting HRT to relieve symptoms such as hot flushes and night sweats. For these women, recent studies suggest there are cardiovascular benefits of taking HRT around the time of menopause.