In a 20-year study of 2,737 women, early HRT was linked to fewer heart attacks and strokes. The lead author says don't take it for that.

Here's a study worth reading carefully, because the headline and the fine print point in different directions. New Scientist reports on research in JAMA Internal Medicine that followed 2,737 women in the Study of Women's Health Across the Nation, all aged 42 to 52 at enrollment and all experiencing hot flushes and night sweats. Over the 20-year study, 755 took some form of hormone replacement therapy, and 224 fatal and non-fatal cardiovascular events occurred. The researchers estimated that women who started HRT 10 years or less after their symptoms began were 27 percent less likely to have one of those events than women who didn't take it. Among women who started more than 10 years after symptoms began, the effect was much less clear, and the apparent benefit was most pronounced among Black participants. Timing seems to be "very critical," said lead researcher Samar El Khoudary of Virginia Commonwealth University. Now the caveats, starting with hers: "I want to emphasise: our study does not support using menopausal [hormonal] therapy to prevent cardiovascular disease." This was an observational study, and women who chose HRT may differ from those who didn't in ways the analysis can't fully capture. "The most important thing to understand about observational studies is that they cannot establish causality," said Tara Iyer of Brigham and Women's Hospital. New Scientist also cites another recent study tying oral HRT to small added yearly risks: 0.09 percent for blood clots in the veins, 0.06 percent for ischemic stroke and 0.03 percent for heart attack. El Khoudary now wants randomized, placebo-controlled trials. If hot flushes and night sweats are wearing you down, HRT is a legitimate treatment to discuss with your doctor for those symptoms. Just don't start or stop it to protect your heart based on this study. Bring your full history, including any family heart disease, to that conversation.