Premature birth linked to risk of mental problems

Updated: Jul 06, 2012, 09:20 AM IST

London: One of the largest studies to investigate birth complications and later mental health has found that premature birth constitutes a single, independent risk factor for a range of severe psychiatric disorders.

Researchers at King`s College London and Karolinska Institute in Sweden suggest that neurodevelopmental differences in those born prematurely may be important in understanding the link, a statement from the college said.

The study, published in The Archives of General Psychiatry, found that individuals born very prematurely (less than 32 weeks gestation) were three times more likely to be hospitalised with a psychiatric disorder aged 16 years and older, compared to those born at term (37-41 weeks gestation).

The risk varied depending on the condition, for psychosis it was 2.5 more likely, for depression three times more likely and for bipolar disorder 7.4 times more likely.

The findings also revealed a smaller increased risk for those born moderately prematurely (32-36 weeks).

Previous research has shown an association between premature birth and an increased risk of schizophrenia, but this is the first study to report an association with a broad range of psychiatric disorders, including bipolar disorder, psychosis and depression, the release added.

Dr Chiara Nosarti, lead author of the paper at the Institute of Psychiatry at King`s, said: "We found a very strong link between premature birth and a range of psychiatric disorders. Since we considered only the most severe cases that resulted in hospitalisation, it may be that in real terms this link is even stronger."

"However, it is important to remember that even with the increased risk, these disorders still only affect 1-6 per cent of the population," Nosarti said.

The researchers analysed data from nearly 1.5 million birth and medical records in Sweden between 1973 and 1985 and identified all those admitted to hospital with their first episode of a psychiatric disorder by 2002.

"We believe that the increased risk of mental disorders in those born very prematurely can be explained by subtle alterations of brain development. The immature nervous system in those born prematurely is particularly vulnerable to neonatal brain injury resulting from birth complications," Nosarti added.

The strongest association the researchers found was to mental health disorders known to have a strong biological basis, such as bipolar disorder, further adding to the theory that neurodevelopmental differences in those born prematurely may play an important role for later mental health.