Exceeding Ideal Family Size and Child Growth Outcomes in the Tsimane Amerindians of Bolivia

Megan E. Costa, University of Pennsylvania
Michael D. Gurven, University of California, Santa Barbara

This paper assesses the causes and consequences of exceeding maternal and paternal ideal family size (IFS) in a high fertility population, the Tsimane of lowland Bolivia. Analyzing IFS in this population offers an opportunity to better understand the transition of a high fertility population in real time. Relationships between social and biological factors and IFS are estimated using linear regression; probabilities of exceeding IFS by these factors are estimated using logistic regression. Effects of sociobiological factors and exceeding IFS on child growth outcomes are estimated. The preliminary results indicate little effect of literacy, Spanish proficiency, and proximity to town on IFS or exceeding IFS. Exceeding IFS does not affect child growth outcomes as strongly as biological effects such as maternal BMI. These results imply that child growth outcomes are not sensitive to exceeding either parents’ IFS, promoting the discussion of what “ideal family size” means in high fertility settings.