Children born in August do significantly worse in exams than classmates born 11 months earlier at the beginning of the academic year, a landmark study shows.
August-born boys are 12 per cent less likely than September-born boys to get good GCSEs and girls are 9 per cent less likely.
In addition, August-born youngsters are 20 percent more likely to ditch academic study and learn a trade from the age of 16. They are 20 per cent less likely to go to an elite university.
And it is not just their education that suffers as they are more likely to be bullied at primary school and have lower confidence in their academic ability.
As a result as teenagers, they are also more inclined to smoke, binge drink and take cannabis and fewer are in control of their lives, according to a report published today.
Claire Crawford, of the Institute for Fiscal Studies (IFS)， co-author of the report, said children face a penalty "simply because they are unlucky enough to have been born late in the school year".
To redress the balance, August-born children could spend a year longer at school under proposals put forward by the study's authors.
Or they could sit tests only when they are deemed ready, or have their test scores age-adjusted.
The shake-up would involve ending the arbitrary system which expects pupils to reach academic levels by the end of a "key stage" at school.
They would instead be expected to achieve those levels by a certain age, for example the crucial "level four" by eleven-and-a-half rather than by the time they leave primary school.
Another alternative, suggested by the authors, is to change the admissions process to ensure children only start school after a certain age.