Brazil Study Finds Best Time to Start Hormone Therapy Cuts Disease Risk 60%
New research suggests that starting hormone therapy during perimenopause, rather than after menopause, could significantly lower the risk of developing certain diseases.
A large study presented at the 2025 Annual Meeting of The Menopause Society analyzed data from more than 120 million patient records. The researchers found that women who began estrogen therapy during perimenopause and continued it for at least ten years had about a 60% lower risk of developing breast cancer, heart attack, or stroke. This was compared to women who started hormone therapy later or never used it at all.
For many years, hormone therapy has been used mainly to manage symptoms like hot flashes, night sweats, and mood swings. This new analysis adds to evidence that starting therapy earlier may be key to gaining long-term health benefits.
The Study’s Findings
The researchers divided women into three groups. One group started estrogen therapy during perimenopause and continued for at least ten years. Another group began hormone therapy after menopause. The third group never used hormones. The study then tracked the occurrence of breast cancer, heart attack, and stroke over time.
Women who started therapy early had roughly 60% lower odds of developing all three conditions. In contrast, women who started estrogen therapy after menopause showed only minimal protective effects. The study also noted a slight increase in stroke risk, about 4.9% higher, for women who started therapy after menopause compared to those who never used hormones.
The Role of Estrogen
Estrogen plays a role in many body systems beyond reproduction. It helps keep blood vessels flexible and supports healthy cholesterol levels in the heart. In the brain, it promotes neuroplasticity and supports mood regulation. It also helps preserve bone density and muscle strength.
When estrogen levels begin to decline during perimenopause, these systems are affected. Introducing estrogen early, before these systems decline significantly, may help preserve their function. Waiting until after menopause, when estrogen receptors have been without stimulation for years, may not provide the same benefits and could carry more risk.
Implications for Women in Their 30s and 40s
Women in their 30s or 40s who notice changes like shorter menstrual cycles, sleep problems, mood changes, or increased anxiety may want to talk to a healthcare provider. The research suggests that starting a conversation about hormone therapy earlier, rather than later, may be important for long-term health.
Perimenopause can begin as early as the mid-to-late 30s. Tracking cycles, symptoms, and energy levels can help identify changes. It is important to find a healthcare provider who is knowledgeable about menopause and hormone health. A healthy lifestyle, including strength training, balanced nutrition, and stress management, also supports the effectiveness of any hormone therapy plan.
