Moderate-to-late preterm babies are three times more likely to have language delays and delayed motor skills by the age of two, a study has found.

Premature babies born at 32-to-36 weeks are at greater risk of developmental and behavioural delays than previously thought, an Australian study has found.

Clinicians at Melbourne's Royal Women's Hospital assessed 200 babies born moderately-to-late preterm while in hospital and followed them up at two years of age, with a psychologist assessing the children's health, cognitive and behavioural development.

Researchers found that compared with full term (37 weeks-plus) healthy babies, babies born moderately-to-late preterm were:

• three times more likely to have delays in their language development
• three times more likely to have delays in the development of motor skills
• twice as likely to have delays in cognitive development such as ability to perform tasks and follow directions
• more likely to have difficulty coping in different social settings

It had been thought babies born between 31-to-36 weeks did not experience significant long-term problems associated with premature birth and most studies have focused on the very premature.

Lead researcher, Associate Professor Jeanie Cheong says while not all moderate-to-late preterm babies experience problems, even a small percentage of the 21,000 children born this early each year in Australia will have significant implications for both healthcare and education providers.

"This research can assist parents in understanding why their child may be facing some additional challenges. But it is key that we undertake further research to understand whether these delays persist into school age and what early assistance can be provided to allow these premature babies to catch up to their peers," she said.

Ass Prof Cheong also said the research highlighted the importance of obstetricians working with women to delay delivery, where possible, until past 37 weeks.

The study is published in the Journal of the American Medical Association Pediatrics.