Premature babies are significantly more likely than average to suffer mental disorders such as schizophrenia in later life, a study has found.
The risk is greatest for those born following a pregnancy lasting less than 32 weeks.
Compared with normal-term babies, they are three times more likely to be hospitalised for a psychiatric problem at 16 or older, researchers found.
Very premature babies have more than twice the normal chance of developing schizophrenia and psychoses.
Their risk of bipolar disorder is increased more than seven-fold, while the chances of developing major depression and eating disorders are raised 2.9 and 3.5 times.
Experts stressed that the chances of a premature baby having a serious psychiatric problem were still small.
Rates of hospitalisation for psychosis are raised from two in 1,000 to about four in 1,000. The vast majority of pre-term babies turn out healthy and normal.
Famous examples include Winston Churchill and Albert Einstein.
But an effect was seen that also applied, to a lesser extent, to babies born moderately prematurely at 32 to 36 weeks.
In this case the risk of psychosis was raised 1.6 times, of bipolar disorder 2.7 times and of serious depression 1.3 times.
Researchers believe the pattern is the result of its impact on early brain development.
However, why some children are affected and others not is unknown.