According to new research, early birth babies face a three times higher risk of developing psychiatric disorder later in life compared to those who are born after full duration of pregnancy.

The study shows that the rise in premature births across the world could give rise to a rise in mental ill health. The rate of premature births have increased by as much as premature births due to reasons like the mothers are older and increasing obesity.

An earlier research has shown that early birth babies are a higher risk of having emotional and behavioural problems at age four that could affect their intellectual and social development.

They found that children who were born after 37 weeks had similar long-term health outcomes to those born after their full term. The researchers said that the babies who were born before 39 weeks had higher risk of health problems till the age of five.

Researchers from the Institute of Psychiatry in London and the Karolinska Institute in Stockholm said that babies born earlier than 32 weeks have three times risk of hospitalisation with mental health problems after the age of 16. The risk is different for different disorders; 2.5 times higher for psychosis, 3 times for severe depression and 7.5 times for bi-polar disorder.

Dr Chiara Nosarti, of the Institute of Psychiatry and lead author of the paper , said that even as most premature babies are fine the effects of premature birth on mental health cannot be underestimates. The study is the largest to investigate the link between prematurity and later admission to psychiatric hospital. It involved studying 1.5 million birth records in Sweden between 1973 and 1985.

The findings were published in Archives of General Psychiatry.