Family Size and the Demand for Sex Selection: Evidence From China

In China, many fewer girls are born than would be expected given natural birth rates. This imbalance has worsened dramatically over the last 40 years. The roughly contemporaneous fall in fertility per woman is often mooted as a source of this apparent increased demand for sex selection: fewer births make it harder to have a son by chance. Despite this, causal evidence is limited. This paper exploits geographic variation in changes in fertility, arising as a consequence of China’s agricultural reforms (1978-84), to provide this evidence. Specifically, I show that households living in counties that benefitted more from the reforms, increased their fertility relative to households elsewhere. I then show that these households are also less likely to engage in sex selection. These changes appear to have been due to higher local incomes interacting with the enforcement of the One Child Policy. The timing of the changes in fertility and sex selection are informative: while fertility increased almost immediately, the decline in sex selection only emerged from the mid 1980s— contemporaneous with the widespread availability of ultrasound. These results suggest that the dramatic decline in fertility in 1970s China, as well as the smaller decline due to the One Child Policy in the 1980s, may have had an important role in fuelling the demand for sex selection.