Summer-born children are more likely to be identified as having special educational needs (SEN) and referred to psychiatric services, an international study has found.
Commissioned by the then Qualifications and Curriculum Authority, the study found that while the higher numbers having SEN is likely to be due to misdiagnosis, relatively younger children do have greater levels of mental ill-health.
This could be due to them experiencing greater stress and lower attainment, National Foundation for Educational Research (NfER) findings concluded.
The team collated findings from 18 research projects in 13 countries, which looked at how pupils were affected by being younger in their year. It found that younger children do less well in tests than their classmates, but that this gap narrows over time and is not significant by the time they are in secondary school.
The researchers added that it is less widely recognised that these children are disproportionately identified as having SEN.
The report states: "The evidence suggests this is likely to be due to mis- identification, due to a failure to take proper account of developmental differences, rather than the actual needs of the children and young people concerned.
"This is a matter of concern, not just for younger children but for relatively older children whose support needs may not be adequately recognised."
The research was used by Sir Jim Rose, former primary chief inspector, when he was asked to look at what could be done to help summer-born children starting school as part of his review of the primary curriculum. Only now has it been published in full.
Sir Jim recommended that all children start school in the September after they turn four, saying that the moves to ensure a more play-based curriculum in reception would help younger children more than deferring entry.
The research advised that the current age effects could be reduced by: using age-standardised tests; ensuring children have an appropriate curriculum; and ensuring teachers' practice takes account of relative age effects - for example, by giving younger children the chance to have leadership opportunities and monitor referral rates for SEN.
Mick Brookes, general secretary of teaching union the NAHT, said: "It's an interesting finding for people to have a look at, but I wouldn't want policy to be changed because of this. It is about how schools redress the balance."