Teachers know that birth month can have an impact on a pupils' academic achievement.
Summer-born children are more likely to struggle alongside classmates who could be almost a year older.
But new research suggests they have another disadvantage - they are less likely to become professional athletes.
The study, at Queensland University of Technology, found that a high number of Australian footballers had their birthdays at the start of the school year - January in Australia - with fewer born in the later months.
Researchers suggest that younger children may become disheartened by playing with children who are much more physically advanced.
The findings mirror other studies that suggest a link between being born at the start of a school year and becoming a professional ice hockey, volleyball or basketball player.