A new study presented at the 2025 Annual Meeting of The Menopause Society suggests that starting hormone therapy during perimenopause could lower the risk of certain diseases by about 60%.
Researchers analyzed data from more than 120 million patient records. They found that women who began estrogen therapy during perimenopause and continued it for at least ten years had a lower risk of developing breast cancer, heart attack, or stroke compared to women who started later or never used hormones.
The study divided women into three groups: those who started estrogen therapy during perimenopause and continued for at least ten years before menopause, those who began hormone therapy after menopause, and those who never used hormones. The researchers then tracked the occurrence of breast cancer, heart attack, and stroke over time.
The results showed that women who started therapy early, during perimenopause, had about 60% lower odds of developing all three conditions. In contrast, women who began estrogen therapy after menopause showed only minimal protective effects. This group also had a slight increase in stroke risk, about 4.9% higher, compared to women who never used hormones.
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 helps balance serotonin and dopamine. It also helps preserve bone density and muscle strength, which can reduce the risk of osteoporosis and frailty later in life.
Researchers suggest that introducing estrogen early, before these systems begin to decline, may help preserve their function. Waiting until after menopause, when estrogen receptors have been without stimulation for years, may not deliver the same benefits and could pose more risk.
Perimenopause can begin as early as a woman’s mid-to-late 30s. Signs include shorter menstrual cycles, sleep changes, mood fluctuations, and increased anxiety. The study’s findings reinforce that starting a conversation with a healthcare provider early may be important for optimizing long-term health outcomes.
Hormone therapy is not a one-size-fits-all approach. The study adds to evidence that timing may be a key factor in its effectiveness. For women in their 30s or 40s experiencing signs of hormonal transition, discussing options with a qualified provider may be a step worth taking.
