Friday, December 7, 2012

What your birthday says about your family background

Research has found that season of birth is associated with later health and professional outcomes; what drives this association remains unclear. In this paper we consider a new explanation: that children born at different times in the year are conceived by women with different socioeconomic characteristics. We document large seasonal changes in the characteristics of women giving birth throughout the year in the United States. Children born in the winter are disproportionally likely to be born to women who are teenagers, who are unmarried, and who lack a high school degree. We show that controls for family background characteristics can explain up to half of the relationship between season of birth and adult outcomes. Our findings suggest that, though popular, using season of birth as an instrumental variable may produce inconsistent estimates. Finally, we provide evidence that seasonality in maternal characteristics is driven by high-socioeconomic status women disproportionately planning births away from winter.
--Kasey Buckles and Dan Hungerman on not-so-random birthdays