Study Links Estrogen-Only Menopause Therapy to Slightly Higher Autoimmune Risk

Menopausal hormone therapy can relieve symptoms during midlife, but its relationship with immune health remains uncertain. A retrospective study reported at the Menopause Society annual meeting compared autoimmune diagnoses among more than 100,000 women using systemic hormone therapy. Researchers examined whether estrogen alone differed from estrogen combined with a progestogen, rather than comparing treatment with no hormone use.

Autoimmune disease occurred in 4.9% of women using estrogen alone and 4.5% using combined therapy. That represents an absolute difference of 0.4 percentage points, or about four additional diagnoses per 1,000 women over the study's observation period. The reported hazard ratio was 1.076, indicating a modest relative difference in the rate of diagnosis during follow-up. The article did not specify follow-up duration.

Of 20 conditions assessed, five showed statistically significant differences: lupus, psoriasis, psoriatic arthritis, multiple sclerosis, and lichen sclerosus. Absolute differences for these individual conditions were small. Sex hormones influence immune function through different pathways, making the comparison biologically plausible. However, the findings do not demonstrate that estrogen causes autoimmune disease or that adding progestogen prevents it.

For women considering or already using hormone therapy, the practical message is individualized discussion, not an immediate medication change. Review symptoms, medical history, and treatment goals with a clinician. These results cannot establish whether either regimen raises or lowers autoimmune risk compared with taking no hormones. They also do not establish that switching regimens would improve health.

Important uncertainties remain because this was observational research presented as a conference poster, not a randomized trial. Differences between treatment groups could explain some associations, and testing many conditions increases the chance of chance findings. The supplied article is truncated and omits methods. Independent experts called for replication; previous randomized studies have produced mixed findings on immune outcomes, underscoring the need for stronger evidence before recommendations change.