
Some experts believe delayed school entry benefits this group of children.
However, the study found children who missed a year of learning often did worse in tests at the age of eight.
The research team, led by scientists at Warwick University, analysed the records of children born in the German state of Bavaria in 1985 and 1986.
They studied 999 children, of whom 472 were born before their due dates.
The researchers looked at teachers' assessments of the children's achievements in their first year of school and compared these with results of standardised maths, reading, writing and attention tests when the children were eight.
The researchers say many parents are keen to hold their children back a year if they are born prematurely or in the summer months, believing they are not mature enough.
Previous research has backed this view for children who are born more than three weeks before their due date.
However, the new analysis found delayed school entry could mean children missed out on learning opportunities "during the critical early years".
At the time the data was collected, children in Bavaria were assessed for school-readiness by a community paediatrician in the year before they were due to start school at six. ?BBC Online