Data from: Flexibility of fetal tolerance: Immune function during pregnancy varies between ecologically distinct populations

Background and objectives: Among placental mammals, females undergo immunological shifts during pregnancy to accommodate the fetus (i.e. fetal tolerance). Fetal tolerance has primarily been characterized within post-industrial populations experiencing evolutionarily novel conditions (e.g. reduced pathogen exposure), which may shape maternal response to fetal antigens. This study investigates how ecological conditions affect maternal immune status during pregnancy by comparing the direction and magnitude of immunological changes associated with each trimester among the Tsimane (a subsistence population subjected to high pathogen load) and women in the United States. Methodology: Data from the Tsimane Health and Life History Project (N=935) and the National Health and Nutrition Examination Survey (N=1395) were used to estimate population-specific effects of trimester on differential leukocyte count and C-reactive protein (CRP), a marker of systemic inflammation. Results: In both populations, pregnancy was associated with increased neutrophil prevalence, reduced lymphocyte and eosinophil count, and elevated CRP. Compared to their US counterparts, pregnant Tsimane women exhibited elevated lymphocyte and eosinophil counts, fewer neutrophils and monocytes, and lower CRP. Total leukocyte count remained high and unchanged among pregnant Tsimane women while pregnant US women exhibited substantially elevated counts, resulting in overlapping leukocyte prevalence among all third-trimester individuals. Conclusions and implications: Our findings indicate that ecological conditions shape non-pregnant immune baselines and the magnitude of immunological shifts during pregnancy via developmental constraints and current trade-offs. Future research should investigate how such flexibility impacts maternal health and disease susceptibility, particularly the degree to which chronic pathogen exposure might dampen inflammatory response to fetal antigens.This dataset contains total and differential leukocyte count (WBC = total leukocyte count, NEU = neutrophils, LYM = lymphocytes, MON = monocytes, EOS = eosinophis, BAS = basophils), leukocyte proportions (neu_pct = % neutrophils, lym_pct = % lymphocytes, eos_pct = % eosinophils, mon_pct = % monocytes, bas_pct = % basophils), C-reactive protein concentration (crp), number of live births (NumPartos), age (Age), body mass index (BMI), participant identification number (pid), reproductive state (RepStatus), age category (AgeCat), population/original dataset (Population), number of repeat measures (Repeats), and presence/absence of repeat measures (REF). There are some missing values (coded as NA), since not all participants had data on both leukocyte differential and C-reactive protein concentration. Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: BCS-0422690Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: Graduate Research Fellowship ProgramFunding provided by: National Institute on AgingCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000049Award Number: P01AG022500Funding provided by: National Institutes of HealthCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000002Award Number: R01AG024119Funding provided by: National Institutes of HealthCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000002Award Number: R56AG024119Funding provided by: Agence Nationale de la RechercheCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001665Award Number: ANR-17-EURE-0010This dataset was compiled by Carmen Hové and consists of data collected by the Tsimane Health and Life History Project (http://tsimane.anth.ucsb.edu/index.html) and the National Health and Nutrition Examination Survey (https://wwwn.cdc.gov/nchs/nhanes/)