Infants born very prematurely, before 32 weeks' gestation, have higher rates of psychiatric disorders by school age compared with their peers.

A study by the Murdoch Children's Research Institute in Melbourne shows a number of factors that predict which very premature children are at higher risk. These factors include brain abnormalities soon after birth, a history of social-emotional problems and social risk.

Social risk factors include family structure, education of primary caregiver, language spoken at home and mother's age when the child was born.

The results offer hope as the risk factors can be identified early in life, increasing the opportunity for intervention, says the lead researcher, clinical psychologist Dr Karli Treyvaud.

The study, which included 177 very preterm children (VPT) and 65 children born at term, found almost one quarter of the VPT children were diagnosed with a psychiatric disorder by age seven. This is three times higher than their peer group.

The most common diagnoses were anxiety disorders (11 per cent), attention deficit hyperactivity disorder (10 per cent) and autism spectrum disorders (4.5 per cent).