SelectionFull text read · 23 Oct 2026
Short answer. In most sports, being born early in the selection year makes you more likely to be picked, and the effect is strongest between about 10 and 14, when a few months of growth looks like talent on the day. In some sports it fades by adulthood. In football it never fully goes away.
A meta-analysis of 57 studies and 308 samples across 25 women's and girls' sports found the oldest quarter of a year group were about 25% more likely to be selected than the youngest. Small overall, but larger before 12 (33%), at higher levels, and in team sports and physically demanding sports. Volleyball, swimming, handball and ice hockey showed the biggest gaps. Gymnastics, shooting and rugby showed almost none. Table tennis leaned the other way.
In men's professional football, the effect is still there at the top. Of 18,429 players in Europe's top divisions, 31% were born in the first quarter of the year and 20% in the last. The gap was widest at the clubs that play in the Champions League and narrowest in the weakest leagues. It held for every position.
But the late-born players who made it were worth just as much. Market value didn't differ by birth quarter, and the most expensive players in Europe were forwards born October to December. Fewer get through; the ones who do are no less good.
In the NHL, drafted players born in the last quarter of the year went on to play about 100 more games than those born in the first, roughly a season more. Basketball and American football showed no birth-month effect at all.
If your kid is young for the year, expect them to look a step behind at 11 to 14 and don't read it as a verdict. Measure them against their own last result.
You're picking the best players in front of you, and on the day the early-born kid often is. The catch is that "best at 12" is partly a birthday, and the squad you pick now is the squad that gets the coaching. If you can, keep a place for the youngest and give them the same minutes. Best today and best at 18 aren't the same list.
The women's meta-analysis found the effect disappears in adults. The football study found it doesn't. So "the gap closes" is true in some sports and false in others, and the honest answer for your sport is the one from your sport.
The hockey "100 more games" result is for players who were drafted anyway. The authors themselves say it may partly be a statistical artefact of there being more early-born players in the sample. Treat it as a hint, not a promise.
Scott Bain · PE teacher, leads a school athlete development programme, reads the papers in full. About