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Abstract ObjectivesConnecting traits to biological pathways and genes relies on stable observations. Researchers typically determine traits once, expecting careful study protocols to yield measurements free of noise. This report examines that expectation with test–retest repeatability analyses for traits used regularly in research on adaptation to high‐altitude hypoxia, often in settings without climate control. MethodsTwo hundred ninety‐one ethnic Tibetan women residing from 3500 to 4200 m in Upper Mustang District, Nepal, provided three observations of hemoglobin concentration, percent of oxygen saturation of hemoglobin, and pulse by noninvasive pulse oximetry under conditions designed to minimize environmental noise. ResultsHigh‐intraclass correlation coefficients and low within‐subject coefficients of variation reflected consistent measurements. Percent of oxygen saturation had the highest intraclass correlation coefficient and the smallest within‐subject coefficient of variability; measurement noise occurred mainly in the lower values. Hemoglobin concentration and pulse presented slightly higher within‐subject coefficients of variation; measurement noise occurred across the range of values. The women had performed the same measurements 7 years earlier using the same devices and protocol. The sample means and SD observed across 7 years differed little. Hemoglobin concentration increased substantially after menopause. ConclusionsAnalyzing repeatability features of traits may improve our interpretation of statistical analyses and detection of variation from measurement or biology. The high levels of measurement repeatability and biological stability support the continued use of these robust traits for investigating human adaptation in this altitude range. 

Abstract Background: The U.N. health and well-being goals for 2030 focus on maternal and child health outcomes, among others. Challenges to meeting those goals vary widely throughout Nepal owing to the range of sociocultural factors, infrastructural limitations, physical geography and altitudes. This article explores sociocultural and biological influences on fertility and child survival among ethnically Tibetan women in Nepal. Methods: This is a cross sectional study of 430 women, age 46-86 years old, citizens of Nepal and native residents above 3500m in Mustang District, who provided interview and physiological data. Univariate Poisson regression analyses selected significant variables to include in multivariate Poisson regressions investigating the number of pregnancies, livebirths, child survival and death outcomes. Results: Earlier age at first pregnancy, later age at last pregnancy, and miscarriages associated with more pregnancies. Miscarriages and stillbirths associated with fewer livebirths. Higher maternal BMI and FEV6 associated with fewer children dying before age 15. Marital characteristics (status, type, continuity), contraceptive use, relative wealth, and education influenced these covariates. Conclusions: Low maternal pulmonary function and nutritional status predict poorer child survival in Upper Mustang. Addressing poor lung function and nutrition may improve reproductive outcomes among ethnically Tibetan women living at high altitude. Keywords: Child survival; fertility; high-altitude; Nepal; women..