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Biological, environmental and socioeconomic determinants of the human birth sex ratio in the Czech Republic

Published online by Cambridge University Press:  13 June 2019

Petr Houdek*
Faculty of Social and Economic Studies, Jan Evangelista Purkyně University, Ústí nad Labem, Czech Republic
Ondřej Dvouletý
Faculty of Business Administration, University of Economics, Prague, Czech Republic
Marek Pažitka
Faculty of Social and Economic Studies, Jan Evangelista Purkyně University, Ústí nad Labem, Czech Republic
*Corresponding author. Email:


The Trivers–Willard Hypothesis (TWH) states that parents in good conditions bias the sex ratio towards sons and parents in poor conditions bias the sex ratio towards daughters. This study used data from a large nationwide population dataset (N=1,401,851) from the Czech Republic – a modern contemporary society. The study included air pollution and property prices in the TWH estimation, and had a more detailed focus on stillbirths than previous studies. Using official natality microdata from the Czech Statistical Office for years between 1992 and 2010 and data on levels of air pollution in the country over the same period, the study assessed whether the biological and socioeconomic status of mothers and environmental factors affected the sex of children. The results were largely insignificant and not robust across specifications. The presented epidemiological evidence suggests that stillbirths are randomly distributed in the Czech Republic and that the sex ratio is not affected by the socioeconomic status of mothers or by environmental characteristics.

Research Article
© Cambridge University Press 2019 

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