New findings presented at the Menopause Society’s 2025 Annual Meeting suggest that starting estrogen hormone therapy during perimenopause (the years leading up to a woman’s final menstrual period) could protect against cancer, heart attack, and stroke.
Using the electronic health records of more than 120 million women, investigators looked at whether those who started hormone therapy (HT) earlier had improved health outcomes and a lower risk of death from preventable diseases.
Researchers compared women who started therapy during perimenopause, those who began after menopause, and those who never used estrogen.
They found that the women who were prescribed estrogen for at least 10 years before menopause had a roughly 60 percent lower risk of developing breast cancer, heart attack, or stroke than the two other groups.
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What the Findings Can — and Can’t — Tell Us
Shortly after the study was presented, social media influencers heralded the findings as proof that women need to start hormone therapy during perimenopause. The menopause influencer Mary Claire Haver, MD, an obstetrician-gynecologist and menopause specialist in Galveston, Texas, posted a video about the study that’s racked up nearly 63,000 likes.
The study “confirms what I see in my clinic almost every day: Timing matters when it comes to menopause,” said Dr. Haver in the Instagram video.
After citing the decreased risk, Haver concluded her post by stating, “This study adds to the growing evidence that starting hormone therapy in perimenopause isn’t just about hot flashes. Really, it’s about long-term health and prevention. It’s time we stop telling women to wait it out and [instead] talk about proactive, evidence-based care.”
But other menopause experts, including the study authors, say the study shouldn’t be cited as proof that taking estrogen early decreases cancer and cardiovascular disease risks.
“While it’s exciting that we’re asking these questions, the study is limited,” says Karen Adams, MD, an obstetrician-gynecologist and the director of the Stanford Program in Menopause and Healthy Aging in California, who wasn’t involved in the research. “It’s being misinterpreted and overinterpreted,” she says.
This wasn’t a placebo-controlled study that randomly divided women into the three groups and then followed the outcomes. Instead, it used insurance claims for prescriptions that the women filled, and gathered information on what women were already doing. That means a lot of factors could have influenced the findings.
Findings Potentially Biased by ‘Healthy User Effect’
“We must be extremely careful about drawing sweeping conclusions from an insurance claims data search. All these results could be due to what’s called ‘the healthy user effect,’” says Dr. Adams.
In this case, that means that women at high risk for those chronic conditions may not have been prescribed hormones in the first place, and so the study subjects may really include only healthy women, she says. Also, anyone who developed a condition that made hormone therapy risky would have been taken off the treatment, adds Adams.
It’s also worth noting that filled prescriptions don’t prove the women took the hormones regularly, or at all, she says.
Finally, there could be major differences in other exposures that can affect the risk of heart disease. “Some women may have smoked, they may have had other risk factors, and we have no way of knowing that,” says Adams. “That’s why we can’t look at a study like this and say if you take hormones early you’ll have these outcomes.”
Rachel Pope, MD, MPH, a menopause specialist at University Hospitals Cleveland Medical Center in Ohio and the senior author of the research, echoes Adams’s thoughts on the study’s limitations.
She adds that the study was only able to follow women for a relatively short period of time, 10 to 15 years at the most. “Since the perimenopausal women are a younger group, we might not be seeing them at the time of life when these health concerns will come up,” says Dr. Pope.
Should You Start Hormone Therapy During Perimenopause?
The findings raise another question: Should women take hormone therapy for 10 years or more before menopause? Given that the average age of menopause is 52 years old, that would mean taking HT in your early forties.
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“Many women begin to experience what we consider ‘menopausal symptoms,’ during perimenopause,” which could be 10 years or more prior to menopause,” says Pope.
Since menopause describes 12 consecutive months without a period (unless a woman had her ovaries removed and went through surgical menopause), it’s hard to predict exactly when a woman will go through the transition, she says.
“Therefore, many women actually do start treatment before menopause and we just don’t have a lot of research on these women,” she says.
“Typically, starting HT at age 40 is not indicated unless the person has primary ovarian insufficiency [when the ovaries stop working normally before age 40 and don’t produce enough estrogen] or early menopause,” says Monica Christmas, MD, the associate medical director of the Menopause Society and an associate professor of obstetrics and gynecology at UChicago Medicine in Illinois.
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A woman this age with a regular period would not need to start HT, because her ovaries would still be producing estrogen and progesterone. This is why checking hormone levels in those cases isn’t recommended — they’d be in the normal range, says Dr. Christmas.
That said, there is a wide range for when women go through menopause, anywhere from 45 to 55 years old, she says. “It is normal to start to experience symptoms related to hormonal fluctuations several years prior to the final menstrual cycle,” says Christmas.
That means symptoms potentially could start around age 40, she says. “However, HT may not be the most appropriate treatment, as it could exacerbate bleeding symptoms or mood swings. In someone still having normal menstrual cycles, continuous hormonal birth control may be a better option,” says Christmas.
More Research Is Needed to Prove Any Potential Health Benefits of Early HT
Before any widespread recommendations about hormone therapy during perimenopause can be made, there needs to be randomized controlled trials of women of similar ages and baseline risks, says Pope.
“Women would be randomized to either receive hormonal or nonhormonal treatment over the same course of time and then followed for as long as possible, preferably decades,” she says.
Having Menopause Symptoms? Here’s What to Do
If you’re experiencing menopause symptoms but still getting your period, does that necessarily mean you’re in perimenopause? How do you know if you’re too young for hormone therapy, or if your window for taking hormones has closed?
“Women in their late thirties or older who are having hot flashes, night sweats, sleep changes, skin changes, vaginal dryness, increase in UTIs or new urinary symptoms, sleep disturbances, or mood symptoms that are not otherwise explained by another medical condition should talk to their healthcare provider about how to address their symptoms,” says Pope.
Research suggests that the safest time to start hormones is within the first 10 years of menopause. “We don’t know for sure about starting prior to that, but if your quality of life is being affected, it is worth a visit to a Menopause Society–certified practitioner to discuss treatment,” says Pope.
The Menopause Society website has a directory to help you find an expert in your area.
Beyond 10 years after you’ve entered menopause, starting hormone therapy requires a conversation and shared-decision making of the risks versus benefits, says Pope.
