Hormone replacement therapy was welcomed with a feminist wave of enthusiasm in the 1960s. It was safe, natural and rejuvenating, its supporters argued — and women deserved no less.

In the US the gynaecologist Robert Wilson wrote a best-seller, Feminine Forever.In Britain Wendy Cooper’s book, No Change, ran nine editions and its author never wavered in her defence of HRT.

Early studies seemed to back the idea that it was safe and suggested that it reduced the risk of heart disease and strengthened bones. Doctors were convinced that women on HRT lived longer, healthier lives. But the women they were studying were not typical: they were already healthier, so would have lived longer anyway.

Better and more comprehensive research has demolished these claims. The Women’s Health Initiative study reported in June 2002 that HRT increased the risks of breast cancer, heart disease and stroke. In August 2003, the Million Women Study found that the risk of breast cancer was doubled if HRT was taken for ten years. So in Britain alone HRT may have been responsible for an extra 20,000 cases.

Advocates of HRT continue to criticise some of these findings, and this month a new US study published in the Journal of the American Medical Association added to the controversy by finding that HRT really did reduce the risk of heart attacks in women in their fifties. The increased heart-disease risk occurred only in older women, the researchers said. They based their findings on a new and more detailed analysis of the Women’s Health Initiative study.

But the new findings did not, as some headlines implied, reverse the earlier warnings. They simply showed that for a subset of women, those nearest the menopause, heart risks were reduced. It did not affect other findings such as the increased risk of breast cancer or blood clots.

Since breast cancer was the main reason why women started to give up HRT, this slight shift is not a U-turn, and does not mean that HRT is safe. Some women may feel that the benefits they get from it exceed the risks, but it is clear that the risks are real.

The warnings seem to be working. A year after the Women’s Health Initiative report, new cases of breast cancer in the US fell by 7 per cent after rising for 20 years.

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