Controversy and confusion have shrouded hormone replacement therapy (HRT)—which involves using estrogen to help alleviate menopause symptoms—since a flawed 2002 study suggested it could up your risk for conditions like cancer and stroke. Though these results were refuted (among other issues, the study included mostly women several years postmenopause), they left a lingering mark in the form of a black box warning on HRT that many doctors are actively pushing to get removed. And new research being presented this week at the 2025 annual meeting of The Menopause Society further supports their case by clarifying a key point: The risks and benefits of HRT aren’t just driven by whether you take it but when.

The analysis of more than 120 million patient records found that women in perimenopause (a.k.a. the leadup to menopause) who had used HRT for at least 10 years before hitting menopause (which marks the one-year mark after your last period) had 60% lower odds of developing breast cancer, heart attack, and stroke compared to those who started HRT after menopause and those who never took hormones.

To be sure, this type of look-back review of health records can’t prove causation, Monica Christmas, MD, a board-certified ob-gyn at UChicago Medicine and associate medical director at The Menopause Society, tells SELF. So we don’t know that using HRT during perimenopause actively prevents those negative outcomes. But it is “promising” evidence that starting HRT at an earlier age is associated with “hopeful benefits,” she says.

There may be a key window of opportunity for beginning HRT.

The fact that the women in the study who started HRT several years prior to menopause had less risk of poor health outcomes is “very reassuring” because it adds to the evidence for “treating patients when they start getting symptoms [during perimenopause] and not waiting until later, when they can become much worse,” Sameena Rahman, MD, a Chicago-based board-certified gynecologist and menopause specialist, tells SELF. “More and more data is pointing to the fact that we should be having discussions about addressing menopausal changes with patients by their mid-30s,” she adds.

After all, symptoms like hot flashes, night sweats, and brain fog can strike well before your period starts to let up, and even when cycle changes do arrive, “they can initially be extremely subtle,” Stacey Silverman Fine, MD, a board-certified ob-gyn at virtual family planning platform Maven Clinic, tells SELF. Hence why so many women don’t realize their discomfort could be perimenopause unless a doctor proactively brings it up. Add to that the ways in which menopause symptoms have historically been brushed off and the fears around HRT, and it’s no wonder so many women have delayed or avoided treatment. What this research suggests is that getting on HRT earlier can help prevent that suffering and may even offer some long-term protection, Dr. Rahman says.