Costs of Reproduction and Maternal Depletion in a High Fertility and Mortality Population

Michael D. Gurven, University of California, Santa Barbara
Megan E. Costa, University of Pennsylvania
Daniel Eid R., Universidad Mayor San Simon, Bolivia
Jonathan Stieglitz, University of New Mexico
Bret Beheim, University of New Mexico
Benjamin Trumble, University of California, Santa Barbara
Hillard S. Kaplan, University of New Mexico

Sex differences in mortality, health and well-being have been documented worldwide. Explanations focus on differences in lifestyle and work-related behaviors, biology and healthcare access. Another explanation is that costs of reproduction unique to women contribute to differential rates of adult physical decline. A life history framework predicts that energy invested in reproduction should trade-off against investments in survival. We present sex differences in adult health and physical condition among the Tsimane, a Bolivian natural fertility population, and test whether cumulative number of live births predicts variability in nutritional status and health using cross-sectional and longitudinal data (2002-2012) from the Tsimane Health and Life History Project. While greater total reproduction exerts specific costs on women's health (anemia, inflammation, cystocele), it bears little impact on nutritional status (weight, BMI, body fat percentage). We discuss the role of self-selection in obscuring trade-offs, and situate our results within the larger literature on maternal depletion.