Family planning could play a decisive role in whether or not an infant will go to university in later life. Children born in September are 20 per cent more likely to enter ÖйúAƬ than those born in August.

A detailed study of month-of-birth statistics has revealed that children born at different points of the year face different odds of progressing from school to university by the time they reach 18.

Linking birth data from the late Seventies and early Eighties to entry figures from 1994 to 2000 suggests the same pattern year on year. Children born in autumn - the oldest in their school year group - were more likely to go to university than their peers born in summer.

The research concludes that if all children in England had the same chance of going to university as those born in September, there would be an extra 12,000 students entering ÖйúAƬ each year - at a stroke increasing the proportion of all 18 and 19-year-olds going to university by 2 per cent.

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The Hefce research concedes that the reason for this seasonal influence on university participation is unclear - beyond the intuitive conclusion that the oldest children in their academic cohort may well be the most mature.

But it cites a separate study of GCSE performance of 500,000 teenagers in 1991 that shows that September-born children not only take more subjects but achieve higher grades than pupils with birthdays in August. As a result, September-born pupils are 18 per cent more likely to sit an A level in at least one subject than their counterparts born in the summer months.

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Intriguingly, the study shows that the same pattern is not repeated in the A-level results, where there appears to be little link with the month of birth. It also suggests that by the time teenagers reach university, there is no performance advantage linked to when their birthday falls in the academic year.

But the impact of changes in pre-school and early-years education in the past decade remains to be seen.

"One of the policies of the Conservative Government in the Nineties and then the Labour Government since 1997 has been to provide support for nursery education and the numbers of primary schools - essentially infant schools - with reception classes," says Alan Smithers, director of the Centre for Education and Employment Research at Buckingham University.

"Pupil numbers have been decreasing in the primary age range, but some children will now be going to school for a few mornings a week from the age of about three.

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"I think that there has been tremendous variation around the country because it has been subject to local education authority policy. Some have had policies of waiting to admit children when they are five, others have admitted the so-called rising fives in January of the school year. The system has become more diffuse.

"Nevertheless, in so far as there is a generality about this, it is that academically stronger children tend to be the older children in their class," Smithers concludes.

Perhaps the better prospects of September-born children were a phenomenon of the late Seventies and Eighties, before the reform of pre-school education. It remains to be seen whether today's toddlers will owe their later life chances to the month of their birth.