Babies born prematurely have higher rates of long-term problems with development and behaviour.

premature birth

A study of premature babies has revealed a link between pre-term births and mental illness, which an expert says has implications for the way mothers and babies should be treated.

The Swedish study of more than 500,000 babies showed infants born very early, between 24 and 28 weeks, were more than twice as likely to be admitted to hospital for a psychiatric disorder in their early 20s than those born at full term.

The study by researchers at Sweden's Karolinska Institute showed 5.5 per cent of those born very early had been admitted to hospital for a psychiatric disorder, compared to 2.4 per cent of those born at full-term.

The psychiatric conditions included mood disorders, stress-related complaints and suicide attempts or deaths.

Even those in the moderate prematurity group, born at 33 to 36 weeks, were at risk with three per cent having been admitted to hospital for a psychiatric disorder.

The study, which followed up premature babies born from 1973 to 1979 through their medical records, made adjustments for other mental illness risk factors including family history and low socio-economic status.

"Pre-term birth carries some risk for psychiatric disorders requiring hospitalisation in adolescence and young adulthood," the researchers concluded in the study published in the journal Paediatrics.

Sydney University's Brain and Mind Research Institute executive director Professor Ian Hickie said the study was one of the few to focus on the long-term mental development of premature babies.

Prof Hickie said premature birth disrupts a critical phase of brain development in the mid to late stages of pregnancy.

"If you're born prematurely it's likely that in some time that period of brain development is interrupted," he said.

"So the critical brain connections and the critical brain pathways are probably harmed by premature birth.

"The effect on some of those brain pathways is probably continued throughout brain development."

A renewed focus on the importance of maternal health, particularly in indigenous populations, would decrease the chances of prematurity, Prof Hickie said.

"There are some really common issues like smoking in pregnancy and alcohol use in pregnancy which continue to be common and contribute to premature birth and difficulties in the womb," he said.

Babies born pre-term would benefit from being monitored through every stage of their development.

"There needs to be an emphasis not only on monitoring their health and welfare in their early years but through into their teenage and early adult years, when there might be increased risk of developing one of the major psychiatric illnesses."

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