Family Planning: Football Style. The Relative Age Effect in Football

TLDR

Recent studies indicate that month of birth is related to achievement in a number of sports. Birth dates were collected for all players on teams competing in the 1990 World Cup and the 1989 Under‑17s and Under‑20s World Tournaments in Football. Players born early in the football activity year (August 1–July 31) were over‑represented while those born later were under‑represented, with the effect strongest in the Under‑17s and Under‑20s tournaments and interpreted as a relative age effect.

Abstract

Recent studies indicate that month of birth is related to achievement in a number of sports. Birth dates were collected for all players on teams competing in the 1990 World Cup and the 1989 Under-17s and Under-20s World Tournaments in Football. Results indicated that those born early in the "activity year" (August 1 through July 31 for football) were over- represented, while those born later were under-represented. The effect was particularly strong in the Under-17s and Under-20s tournaments. Results are interpreted in the context of the "relative age effect".