Sex gaps in immune measures were generally smaller among the Tsimane
An observational study compared immune measures in 5,866 Tsimane people and 9,825 US participants aged 2 to 84, accounting for women’s reproductive status.
9,825 participants, cohort study
Limit: The US sample excluded women reporting menopause before 40
Edited by Boris Djordjevic · AgingResearch.News
The observational study included 5,866 Tsimane people from the Bolivian Amazon and 9,825 US participants, all aged 2 to 84 and including both sexes. The Tsimane live in a nonindustrialized population with limited access to effective contraception. Researchers compared white blood cell counts and the ratio of two types of white blood cells, a marker of body-wide inflammation.
Sex differences were generally smaller among the Tsimane than in the US. The authors linked this mainly to population differences in how age and previous births related to women’s immune measures during pregnancy. The inflammation marker was elevated during pregnancy among US women with no previous live births. After menopause, sex differences in immune measures generally reversed or disappeared in both populations.
Why it matters
The work addresses how reproductive history relates to changes in immunity across the lifespan. The authors suggest that later first births and fewer births may contribute to women’s excess autoimmune disease by altering pregnancy’s lasting effects on immunity.
Caveats
This observational study cannot establish that reproductive history caused immune differences or altered autoimmune disease risk. The preprint has not been peer-reviewed, and the US sample excluded women reporting menopause before 40.
The paper
University of California, Santa Barbara
Research Square, May 18, 2026, Open access, Preprint, not peer-reviewed
Comments
Be the first to comment.