Working Paper: NBER ID: w14573
Authors: Kasey Buckles; Daniel M. Hungerman
Abstract: 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 born to women who are more likely to be teenagers and less likely to be married or have 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. We then discuss the implications of this result for using season of birth as an instrumental variable; our findings suggest that, though popular, season-of-birth instruments may produce inconsistent estimates. Finally, we find that some of the seasonality in maternal characteristics is due to summer weather differentially affecting fertility patterns across socioeconomic groups.
Keywords: season of birth; health outcomes; socioeconomic characteristics; instrumental variable
JEL Codes: C10; J11; J13
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| summer weather (Q54) | fertility patterns (J13) |
| fertility patterns (J13) | maternal characteristics (J16) |
| season of birth (J13) | instrumental variable estimates (C26) |
| unobservable factors (D91) | instrumental variable estimates (C26) |
| season of birth (J13) | socioeconomic characteristics of mothers (I24) |
| socioeconomic characteristics of mothers (I24) | later outcomes (education and earnings) (I26) |
| season of birth (J13) | later outcomes (education and earnings) (I26) |
| family background characteristics (J12) | later outcomes (education and earnings) (I26) |