Socioeconomic consequences of the fertility transition: sibling exposure and intergenerational social mobility in Stockholm 1878 – 1926

Joseph Molitoris, Lund University

The effects of the fertility transition have received limited attention when compared to its causes. Yet rapidly changing family sizes could have profound effects on individual outcomes. Several studies have found support for the resource dilution hypothesis, which posits that larger families will have lower per capita investments in child quality (e.g. Van Bavel, 2006; Maralani, 2008). This paper utilizes Stockholm City's population during the fertility transition to examine how sibling exposure influenced an individual's chances of socioeconomic mobility. Rather using a discrete measure of the number of siblings, the paper uses the longitudinal information from the Roteman’s Archive to calculate sibship exposure as a continuous measure of “sibling-years”, i.e. the number of shared person years an individual experienced during his childhood. In a high mortality environment, this offers a more precise measure of the true exposure of individuals to resource dilution than net sibship size at a given age. Multinomial logistic regressions are used to estimate the effects of sibling exposure on socioeconomic mobility from a sample of 5,552 men observed from birth until after age 30. The results indicate that greater exposure to siblings in the first ten years of life was not associated with any significant change in the risk of downward mobility relative to non-mobility, but a decreased risk of upward mobility. Furthermore, the main contribution to decreased risks of upward mobility stems from greater exposure to younger siblings and not from older ones. There appeared to be no significant effects of the length of birth intervals on mobility in later life. Whether or not children’s economic outcomes provided motivation for fertility regulation is impossible to know, but the results suggest that there were real gains to being less exposed to siblings during the fertility transition.