A study has found that people who were born prematurely have a much greater risk of mental disorders in adulthood than those born at term.
Researchers from King’s College London looked at the medical records of 10,000 Swedish people who had been admitted to hospital for bipolar disorder, depression, eating disorders, and alcohol and drug addiction.
They found that adults who had been born at less than 32 weeks gestation were three times as likely to suffer depression and 7.4 times more likely to have bipolar disorder than babies born at 40 weeks.
They were also 2.5 times more likely to suffer psychosis and 3.5 times more likely to suffer an eating disorder.
Babies who were born prematurely at 33 to 36 weeks gestation had 1.3 times the risk of depression, 2.7 times the risk of bipolar disorder and 1.6 times the risk of psychosis.
Past research has found that preterm babies have a greater chance of behavioural problems at school, but this study shows that the problems could last into adulthood.
Study author Dr Chiara Nosarti says that the nervous systems of premature babies are less developed, which puts them at greater risk of brain injuries.
"Since we considered only the most severe cases that resulted in hospitalisation, it may be that in real terms this link is even stronger,” Dr Nosarti said.
"However, it is important to remember that even with the increased risk, these disorders still only affect one to six per cent of the population."
The researchers would like to see doctors take premature birth into account when making diagnoses of adolescents.