Hormone Therapy in Perimenopause: Why Timing Could Be Everything for Your Long-Term Health

If you’re in your 40s and starting to notice changes, sleep that isn’t quite as restorative, a mood that feels less steady, or hot flashes that come out of nowhere, you’re likely entering perimenopause. It’s a phase that can last years before your final period, and for many women, it’s when symptoms are at their most disruptive.

Here’s what many women don’t realise: this transitional window may also be the optimal time to consider hormone therapy, not just for symptom relief, but potentially for protecting your long-term health.

At Reborne Longevity, we believe in predictive, preventative, and personalised medicine. When it comes to hormonal health, the emerging science suggests that when you act may matter as much as whether you act at all.

The Science Has Shifted

For over two decades, hormone therapy carried a stigma rooted in a landmark study from 2002. The Women’s Health Initiative suggested that hormone therapy increased the risk of breast cancer, heart disease, and dementia. As a result, millions of women avoided treatment, often suffering in silence through symptoms that significantly impacted their quality of life.

But the original study had a critical flaw: most participants were older women, with an average age of 63, who started hormone therapy many years after menopause. This isn’t how most women actually use these treatments.

In November 2025, the FDA took historic action, removing the “black box” warnings from most hormone therapy products. This followed a comprehensive review of decades of research showing that the risks were overstated—particularly for women who start therapy earlier in the menopause transition.

As researchers from Yale School of Medicine have noted, the evidence now suggests that hormone therapy can be beneficial for women within 10 years of menopause, with many physicians recommending treatment early in perimenopause to maximise benefits.

The Critical Window: Why Earlier May Be Better

Central to the modern understanding of hormone therapy is something researchers call the “timing hypothesis” or “critical window hypothesis.” Put simply: the benefits of hormone therapy appear to depend heavily on when you start.

A major study presented at The Menopause Society’s 2025 Annual Meeting examined data from over 120 million patient records. The findings were striking: women who initiated oestrogen therapy during perimenopause had approximately 60% lower odds of developing breast cancer, heart attack, and stroke compared to those who started after menopause or never used hormones.

This aligns with what we see in clinical practice. When hormone therapy is started closer to the onset of menopause, deally within 10 years, or before age 60, the benefits appear to outweigh the risks for most women.

Beyond Hot Flashes: The Whole-Body Impact of Oestrogen

Oestrogen isn’t just about reproduction. It influences virtually every system in your body, your heart, your bones, your brain, your metabolism, and your mood. When oestrogen levels decline, the effects ripple outward.

Vasomotor symptoms: Hot flashes affect around 75% of menopausal women and can persist for over a decade. According to the 2025 Korean MHT Guidelines, hormone therapy remains the most effective treatment, reducing symptoms by approximately 75% with standard doses.

Bone health: Bone loss accelerates before the final menstrual period, increasing fracture risk. Hormone therapy is FDA-approved for osteoporosis prevention and has been shown to reduce fractures of the hip, spine, and other sites, even in women who don’t yet have osteoporosis.

Cardiovascular health: Cardiovascular events increase 1.6-fold after menopause. A 2024 systematic review found that early initiation of hormone therapy was associated with improved blood vessel function, lower all-cause mortality, and reduced cardiovascular events. Transdermal formulations (patches, gels) appear to have a more favourable safety profile than oral options.

Metabolic health: Declining oestrogen contributes to central fat accumulation and insulin resistance. A 2024 study of over 6,500 participants found that hormone therapy was associated with a 31% lower incidence of diabetes over 20 years of follow-up.

Sleep, mood, and quality of life: A 2024 study reported significant improvements in sleep quality within three months of starting hormone therapy. Research also shows mood benefits are more pronounced in perimenopausal women than in later menopause, likely due to effects on brain chemistry.

What About Brain Health?

The relationship between hormone therapy and cognitive function remains nuanced. Some observational studies have suggested a protective effect against dementia when therapy is started early, while the original WHI study, which enrolled primarily older women, showed potential harm.

The KEEPS Continuation Study, published in PLOS Medicine in 2024, followed women for approximately 10 years after completing hormone therapy that was initiated in early menopause. The key finding: no long-term cognitive harm or benefit was detected when therapy was started around the time of menopause.

What this tells us is that hormone therapy initiated early doesn’t appear to damage the brain, and may support it during a vulnerable transition. Current evidence doesn’t support using hormone therapy specifically for dementia prevention, but for women seeking symptom relief, cognitive concerns shouldn’t be a barrier to treatment.

Personalisation Matters

There is no one-size-fits-all approach to hormone therapy. Options include oral tablets, transdermal patches, gels, vaginal preparations, and different hormone combinations. The right choice depends on your symptoms, medical history, and individual risk profile.

At Reborne Longevity, we take a precision medicine approach. This means comprehensive assessment, including detailed genetic assessment, hormone panels, cardiovascular risk evaluation, bone density screening, and metabolic markers, before recommending any intervention. We consider hormone health as part of an integrated system that includes cardiovascular, metabolic, neurological, and musculoskeletal function.

For perimenopausal women who still require contraception, low-dose combined oral contraceptives can serve dual purposes. For those past their final period, continuous combined regimens or transdermal oestrogen with micronised progesterone are often preferred.

What If Hormones Aren’t Right for Me?

For women who cannot or prefer not to use hormone therapy, including those with a history of hormone-sensitive breast cancer, newer options exist. The FDA has approved non-hormonal medications (Veozah in 2023, Lynkuet in 2025) specifically for treating moderate to severe hot flashes. These work through different pathways and can provide meaningful relief.

Lifestyle interventions also play a crucial role. Regular strength training, adequate protein intake, quality sleep, and stress management all support hormonal balance and overall healthspan, with or without pharmaceutical therapy.

The Bottom Line

We’re in a new era of understanding when it comes to menopausal health. The research is clear that timing matters, and that the perimenopausal years represent a window of opportunity for intervention that may have lasting effects on your healthspan.

If you’re experiencing symptoms of perimenopause, or simply want to understand your hormonal health as part of a comprehensive longevity strategy, this is the time to have the conversation. Don’t wait until symptoms become unbearable. Don’t let outdated information keep you from exploring your options.

At Reborne Longevity, we integrate hormonal health into our whole-person approach to longevity medicine. Our multidisciplinary team can assess your individual needs, discuss the latest evidence, and develop a personalised plan that supports not just your comfort today, but your vitality for decades to come.

Ready to take a proactive approach to your hormonal health? Book a consultation with our team to discuss your individual needs and explore whether hormone therapy might be right for you.

BOOK A HORMONE CONSULTATION

This article is for informational purposes only and does not constitute medical advice. Decisions about hormone therapy should be made in consultation with a qualified healthcare provider who can assess your individual health history and risk factors.

References

FDA Press Release: HHS Advances Women’s Health, Removes Misleading FDA Warnings on Hormone Replacement Therapy. November 2025.

The Menopause Society: When Women Initiate Estrogen Therapy Matters. 2025 Annual Meeting.

Korean Society of Menopause: The 2025 Menopausal Hormone Therapy Guidelines. PMC.

International Journal of Molecular Sciences: Menopausal Hormone Therapy—Risks, Benefits and Emerging Options: A Narrative Review. November 2025.

Gleason CE, et al. Long-term cognitive effects of menopausal hormone therapy: Findings from the KEEPS Continuation Study. PLOS Medicine, November 2024.

Cho L, et al. Rethinking Menopausal Hormone Therapy: For Whom, What, When, and How Long? Circulation, 2023.

Yale School of Medicine: After Decades of Misunderstanding, Menopause is Finally Having Its Moment. April 2025.

BMC Women’s Health: The benefits and risks of menopause hormone therapy for the cardiovascular system. January 2024.