Income, stress, and sex ratios over 1895-2010

The medical literature has shown that populations under high stress have a lower sex ratio at birth (i.e. number of males for every 100 females). In this paper, I examine the relationship between income, as a source of economic stress, and the sex ratio at a subnational level for the 1895-2010 period. For this, I use census microdata from Argentina -a developing country that experienced rapid growth at the end of the 19th century and stagnated in recent decades- and I estimate from a two-way fixed effects model that exploits the wide temporal and geographic variability in income. The results show that as per capita income increases, the sex ratio at birth also increases. In particular, for every US$ 1,000 increase in per capita income, the sex ratio increases between 0.3 and 0.6 points. These findings make it possible to quantify the lost boys (i.e. those boys who were not born due to high economic stress on their parents) and constitute a call for attention in favor of the implementation of prenatal care policies -especially in periods of stagnation or income decline- to maintain a more balanced sex ratio.