Researchers from the Institute of Psychiatry looked at babies born before 33 weeks and compared their development with those born at full-term.

Very preterm birth (33 weeks' gestation) is associated with later neuromotor and cognitive impairment, reduced school performance, and psychiatric morbidity.

Several follow-up studies have demonstrated increased anxiety and social rejection and reduced self-esteem in preterm children and adolescents, but few studies have examined the effects of preterm birth on adult personality.

In this study 108, VPT 18 and 19-year-olds were compared to 67 born at full-term.

The group were given a questionnaire which indicates 3 aspects of personality: extraversion (sociability, liveliness, sensation seeking); neuroticism (anxiety, low mood, low self-esteem); and psychoticism (coldness, aggression, predisposition to antisocial behavior).

The questionnaire included 48 questions such as 'does your mood ever go up or down?' and 'do you enjoy co-operating with others?'

The researchers found that premature babies, in particular girls, were more likely to be anxious and withdrawn, and potentially at a higher risk of depression, and birth weight was also weakly associated with increased lie scores.

Those born prematurely also appeared to have lower levels of a personality trait called 'extraversion', indicating that they may have less confident and outgoing personalities.

They also had higher levels of the personality trait 'neuroticism', which indicates increased anxiety, lower mood and lower self-esteem.

The researchers suggest that the potential psychological trauma stemming from something as highly invasive as intensive care, should not be ignored.

The researchers, led by psychiatrist Dr Matthew Allin, concluded that young adults who are born VPT have different personality styles from their term-born peers.

This they suggest may be associated with an increased risk of psychiatric difficulties such as depression and anxiety disorders.

Premature baby charities say the findings are interesting and hope more research into the stress and trauma caused by the intensive care experience will be done.

The study is published in the journal Pediatrics.