Hormone Therapy Started Within 10 Years of Menopause Tied to Lower Heart Risk in 20‑Year Study

Women who experience hot flashes or night sweats and begin menopausal hormone therapy during perimenopause or early postmenopause have a 22% lower risk of cardiovascular events compared with similar women who do not start treatment, according to a new analysis published in JAMA Internal Medicine. The benefit was most pronounced among women who initiated therapy within 10 years of menopause onset.

Caution: This was not a randomized trial. Researchers used 20 years of observational data to emulate hypothetical trials, and the study authors stress that the findings should not be used to prescribe hormone therapy solely for heart protection.

Hot flashes and night sweats affect up to 80% of women during the menopausal transition and typically persist for 7–10 years. For two decades, many women and clinicians have avoided hormone therapy because of cardiovascular concerns raised by the Women’s Health Initiative trials in the early 2000s.

Timing Shaped the Result

The research team, led by investigators at Virginia Commonwealth University and the University of Pittsburgh, analyzed data from the Study of Women’s Health Across the Nation (SWAN), collected from 1997 to 2017. The analysis included 2,737 women who reported hot flashes or night sweats, had no prior cardiovascular disease, and had not previously used hormone therapy.

Over roughly 20 years of follow‑up, the researchers compared women who started hormone therapy with comparable women who did not, repeating the comparison at multiple visits to mimic a clinical trial design.

Cardiovascular events encompassed heart attack, stroke, heart failure, procedures to restore coronary blood flow, and related deaths.

Among women who began therapy within 10 years of menopause onset, the adjusted hazard ratio was 0.73 (95% CI 0.58–0.93), indicating about a 27% lower risk. In contrast, women who started therapy more than 10 years after onset had an adjusted hazard ratio of 1.53 (95% CI 0.66–3.52), showing no clear benefit in either direction.

The protective association was strongest among Black women, with an adjusted hazard ratio of 0.51. Estimates for other racial and ethnic groups were imprecise, the authors noted. Black women also tend to experience more severe hot flashes, making these findings particularly relevant for future research.

Limitations of the Findings

Target‑trial emulation reduces some biases inherent in observational studies but cannot fully replace randomization. Women who choose hormone therapy differ from those who do not in income, access to care, and other health factors that influence heart health.

“Our findings are thought‑provoking. However, caution should be exercised in their interpretation,” said Rebecca Thurston, PhD, associate dean for women’s health research at the University of Pittsburgh School of Medicine and a senior author. “These data point to the need for a clinical trial specifically designed among midlife women with vasomotor symptoms.”

Additional limitations include the fact that not all cardiovascular events were confirmed through medical records and possible misclassification of women who used hormone therapy briefly. The researchers also emphasized that any benefit must be balanced against known risks, such as increased breast‑cancer risk with longer use.

An invited commentary in the same journal described the work as strong observational evidence that effects vary by time since menopause and by race/ethnicity, but it noted that definitive trials to guide clinical decisions have yet to be conducted.

SWAN is funded by the National Institutes of Health. Lead author Ziyuan Wang, PhD, is now affiliated with Eli Lilly and Company. Full conflict‑of‑interest details are available in the journal’s disclosure statement.

Implications for Women With Hot Flashes

The results are most relevant for women in their 40s and 50s who experience bothersome hot flashes or night sweats and are weighing whether to start hormone therapy for symptom relief. The findings do not apply to women without these symptoms nor do they support initiating therapy many years after menopause.

Samar El Khoudary, PhD, professor and chair of epidemiology at the VCU School of Public Health and a senior author, said the team hopes the study “helps inform conversations between women and their healthcare providers about the potential benefits and risks of hormone therapy for vasomotor symptoms.”

The study arrives as regulatory guidance evolves. The authors noted that the FDA’s removal of broad boxed warnings from hormone‑therapy products underscores the need for updated evidence to inform safety assessments.

Preparing for a Clinician Conversation

Women considering treatment can prepare by tracking symptom frequency, noting when periods stopped, and gathering family history of heart disease, stroke, blood clots, and breast cancer. Estrogen is available in pills, patches, gels, and other forms; the delivery route can affect both risk and cost.

Cost can be a factor. Many insurance plans cover generic hormone therapy, but prior‑authorization rules vary. Some women pay out‑of‑pocket for compounded products that are not FDA‑approved. Asking whether an FDA‑approved option is covered can reduce both expense and quality concerns.

No one should start or stop hormone therapy without consulting a clinician. Chest pain, sudden shortness of breath, one‑sided leg swelling, or stroke signs such as facial drooping or slurred speech require emergency care.

Current medical guidance has not changed because of this study, and no new trial has been announced. The practical takeaway is that timing appears important, and for women with hot flashes who start treatment closer to menopause, the heart‑related picture may be more reassuring than previously assumed.

Key Questions Answered

What did the study find? Women with hot flashes or night sweats who started hormone therapy in perimenopause or early postmenopause had a 22% lower risk of cardiovascular events than those who did not.

Does timing matter? Yes. Starting within 10 years of menopause onset was linked to roughly a 27% lower risk, while starting later showed no clear benefit.

Was this a clinical trial? No. It used observational data from SWAN to emulate trials, so it cannot prove causality.

Should women take hormone therapy to protect their hearts? No. Researchers caution that the findings do not support using hormone therapy for heart‑disease prevention and should not guide practice on their own.

Who is most affected by these findings? Women in their 40s and 50s with bothersome hot flashes or night sweats who are considering treatment for symptom relief.

What are the known risks of hormone therapy? Risks include blood clots and an increased breast‑cancer risk with longer use. Individual risk depends on age, health history, and the type of therapy.

What should women do next? Discuss symptoms, timing since menopause, and personal and family health history with a clinician before starting or changing any treatment.

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