Babies born "very pre-term" run a high risk of intellectual impairment, such as having learning difficulties or Attention Deficit Hyperactivity Disorder, new research shows.
A University of Canterbury project has found by the age of four, at least a third of very pre-term children - compared to about 15 per cent of full-term children - were subject to some form of cognitive delay.
University psychology Professor Lianne Woodward said the study found that white matter abnormalities seen on children's MRI scans were a strong independent predictor of later cognitive problems.
White matter is the cabling network of the brain which allows different parts of the brain to communicate with each other.
"... children born very pre-term with white matter abnormalities on neonatal MRI were at increased risk of cognitive impairment, with these risks increasing as the severity of white matter abnormalities increased," Prof Woodward said.
"We had previously shown that cerebral white matter abnormalities were an important predictor of cerebral palsy by age two, but results were less clear when it came to predicting cognitive functioning, in part due to the young age of study children," she said.
The study investigated one group of 104 children born at 32 weeks and another group of 107 full-term infants who were admitted to the Neonatal Intensive Care Unit at Christchurch Women's Hospital over a two-year period.
Premature birth is among the leading public health problems in Australasia, Europe and the US, placing immense burden on families, as well as health, education and social services.
"International estimates suggest the average lifetime costs associated with significant motor and cognitive disability are very high, with these costs not including the hidden costs borne by families," Prof Woodward said.
"To date, most follow-up studies in very pre-term born children have tended to focus on the risks of severe impairment and disability.
"However, given the substantial numbers of very pre-term survivors with mild cognitive impairment, this group appears to be important.
"An increasing number of children will likely experience high-incidence, low severity conditions such as learning disabilities, ADHD and developmental coordination disorder that compromise classroom learning."