A large health-records analysis presented at The Menopause Society’s 2025 Annual Meeting found that postmenopausal women using hormone therapy had a higher risk of autoimmune disease than researchers expected, a result the study’s lead author called opposite to what we were expecting.
Here’s what the research actually found, and why the researcher himself says it’s too early to change how anyone approaches hormone therapy.
What the study looked at
The analysis, titled Association of Hormone Therapy With Autoimmune Disease Risk in Postmenopausal Women: A TriNetX-Based Analysis, was presented by Xuezhi Daniel Jiang, MD, PhD, with co-author A. Syed, at The Menopause Society’s 2025 Annual Meeting in Orlando, Florida, held October 21 through 25, 2025. The researchers used TriNetX, a health-records research network, to study autoimmune disease patterns among postmenopausal women using hormone therapy.
What they found
Hormone therapy use was associated with significantly higher incidence of, and risk for, autoimmune disease overall. Increases in risk showed up for nearly every autoimmune condition the researchers looked at, with two notable exceptions: Graves disease and autoimmune hepatitis did not show the same pattern.
One comparison this study didn’t make, despite how it’s sometimes been described elsewhere: estrogen-only therapy versus combined estrogen-progestin therapy. Dr. Jiang has said that’s exactly the next question future research needs to answer, not something this analysis itself settled.
Why the researcher is urging caution
Dr. Jiang was direct about the limits of what a single database analysis like this one can prove. It’s too premature to draw any conclusion, he said, adding that it’s too early to say hormone therapy is contraindicated in women with autoimmune disease. He drew a comparison to the Women’s Health Initiative, where the timing of when a woman starts hormone therapy relative to menopause has turned out to matter a great deal, and said a similar timing effect may be at play here.
His recommendations for now: clinical vigilance, shared decision-making between patients and clinicians, and closer monitoring for new or worsening autoimmune symptoms in women on hormone therapy, especially those with a personal or family history of autoimmune disease.
What’s still unknown
A database analysis like this one can show an association, not prove that hormone therapy causes autoimmune disease. Dr. Jiang’s own list of open questions is long: how dosage and regimen affect risk, whether the timing of when therapy starts matters, and whether hormone therapy might worsen autoimmune disease that’s already present rather than trigger new disease. The estrogen-only-versus-combined comparison that’s often assumed to already exist hasn’t been done yet.
The bottom line
This is a real, notable finding worth knowing about, not a reason to change course on hormone therapy without talking to a clinician first. As Dr. Jiang put it, there’s no yes-or-no answer yet.