Does the Bigger-Fish-in-the-Pond Hatch More Fry? A Register-Based Analysis of the Causal Effect of Students Grade Rank Position in Schools on Completed Fertility, Marriage, and Divorce by Age 40

Educational systems and psychological traits are both important predictors of demographic behavior. However, educational institutions themselves may structure social psychological mechanisms that influence fertility in the long term. Research on Big-Fish-Little-Pond effects proposes that important developmental traits are influenced by comparing one’s academic achievement relative to peers; high relative achievement fosters positive gratification, while low relative achievement leads to deprivation effects. This study examines Big-Fish-Little-Pond effects on childbearing, marriage, and divorce by age 40. We use Swedish register data, school fixed effects and 9th-grade school grade rank to address key challenges including selection bias, short-term follow-ups, and distinguishing between relative deprivation and gratification effects. For women, high school rank shows no clear gratification, but gender-specific relative deprivation effects: For women, low relative rank increases childlessness, delays motherhood, and lowers fertility. For men, a low relative rank reduces marriage likelihood, delays first and second births, decreases fertility, and increases divorce likelihood. We conclude that school systems may exert long-term influence on partnering and fertility through reference group mechanisms. Given the universality of school exposure, such effects may be widespread. Theory on the link between education and fertility highlighting should consider the interplay between educational institutions and social psychological mechanisms.