Babies born more than 13 weeks premature are at a higher risk of developing autism in later childhood. Researchers from Karolinska Institutet and Karolinska University Hospital in Sweden claim that these babies are exposed to various stress factors during a period crucial for brain development, possibly playing a major role in the development of autism spectrum disorder (ASD).

The researchers studied the MRIs of more than 100 babies who had been born extremely prematurely. The babies were examined when they were still neonates and were screened for autistic traits when they reached the age of six.

Children who developed ASD experienced complications during the neonatal period are more common than premature babies who have never had complications. The study's findings suggest that complications and birth weight increase the risk of autism.

Brain differences that are commonly seen in diagnosed autism were already observable even before children exhibited autism signs such as diminished growth of the brain’s parts that are important in social contact, empathy and language acquisition.

“We were surprised by how many – almost 30 per cent – of the extremely preterm-born children had developed ASD symptoms,” Ulrika Ådén said in a press release. “Amongst children born after full term pregnancy, the corresponding figure is 1 per cent.”

Autism is almost five times more common among boys than girls and is generally attributed to genetic factors despite an unidentified autism gene. The 2012 Survey of Disability, Ageing and Carers (SDAC) showed that 115,400 Australians had autism. This was a 79 percent increase from the diagnosed population back in 2009. Experts say that stimulating the development of babies and avoiding stress at birth can reduce the risk of developing ASD.

“Our study shows that environmental factors can also cause autism,” Ådén concluded. “The brain grows best in the womb, and if the developmental environment changes too early to a life in the atmosphere, it can disrupt the organisation of cerebral networks.”

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