The gap between the performance of summer-born children and their peers is still evident at the age of 11, new research shows.
The findings come from an analysis of more than 1.5 million pupil assessments in reading and maths.
Today’s report, written by Timo Hannay, of school data specialist SchoolDash, using information from termly assessment tests, also identifies gender differences in maths, depending on the topic studied.
The performance of children born between April and August has long been a cause of concern, and this year Department for Education data showed an 84 per cent increase in the number of parents asking to delay the admission of their summer-born children into Reception.
Today's report says: “Pupils born in the summer achieve an average of 7.5 percentage points lower in Reception-year maths tests compared to their non-summer-born classmates.
Gap 'reduces but does not disappear'
“This difference reduces during the course of primary school but does not disappear, reaching 3.6 percentage points by Year 6.”
The author found a “similar trajectory” for reading, which held for topics including comprehension, inference and language structure and presentation.
The report says that at the very start of primary school, girls show a slightly higher average performance in maths than boys, but boys overtake girls by Years 2-3 and remain ahead until the end of primary school.
In maths, boys were found to do particularly well in number and measures, while girls do relatively well in operations and geometry.
The analysis used data from more than 1.5 million Progress in Reading Assessment (PiRA) and Progress in Understanding Mathematics Assessment (PUMA) tests – standardised assessments which are used by more than 6,000 primary schools across England and provided by RS Assessment from Hodder Education.