The timing of starting hormone replacement therapy may have an impact on heart health – early initiation during menopause was associated with a lower risk.

New research raises one possible explanation for the conflicting results. It may be important when the treatment is started.

Hormone replacement therapy is primarily used to relieve menopausal symptoms such as hot flashes, mood symptoms and night sweats.

In many large studies so far have followed women around the age of 60, although menopause usually starts earlier.

A new study examines the so-called timing hypothesis. According to it, the effects of hormone replacement therapy may depend on at what point in menopause the treatment is started.

In the United States in long-term follow-up treatment initiation during or shortly after premenopause was associated with a lower risk of cardiovascular disease. For those who started treatment later, the result was more uncertain.

With there were nearly 2,800 women with hot flashes or night sweats, but no history of cardiovascular disease or HRT use.

755 of the women started hormone replacement therapy during follow-up. During approximately 20 years of follow-up, 224 cardiovascular events were recorded for them. Among them are heart attacks, strokes and heart failure.

When hormone replacement therapy was started within ten years of the onset of menopause, the relative risk of cardiovascular events was 27 percent lower than in those who did not start the treatment.

Research however, does not show that HRT is the reason for the lower risk.

“I want to emphasize that our study does not support the use of menopausal hormone therapy to prevent cardiovascular diseases,” says the epidemiology professor who led the study Samar El Khoudary for New Scientist magazine. He works in the USA at Virginia Commonwealth University.

The study used an American Study of Women’s Health Across the Nation (SWAN) monitoring material. It was not a randomized drug trial but an observational trial.

The researchers statistically strive to make the comparison groups as similar as possible. They took into account, for example, age, smoking, weight, blood pressure and cholesterol. There may still be differences between the groups that affect the results.

More research is needed on how hormone replacement therapy affects heart health and the importance of the starting time of the treatment.

Hot ones Hot flashes and night sweats are very common during menopause.

Fresh in the Spanish material they were reported by 77 percent of women. The data focused on women with symptoms, so the reading does not tell directly about all menopausal women.

Fresh of a British meta-analysis according to, symptoms occur in women all over the world, but there is great variation between studies.

The symptoms can be treated with hormone replacement therapy, which is given as tablets, patches, gels or sprays, for example.