Babies born weighing less than 1.8kg could be more prone¹ to developing autism than children born at normal weight, a study suggests.

一项调查显示，出生时体重低于1.8千克的婴儿比正常体重的婴儿更容易患上自闭症。

Writing in Pediatrics journal, US researchers followed 862 New Jersey² children born at a low birthweight from birth to the age of 21.

Some 5% were diagnosed with autism, compared to 1% of the general population.

But experts say more research is needed to confirm and understand the link.

Links between low birthweight and a range of motor and cognitive³ problems have been well established by previous research.

But the researchers say this is the first study to establish that these children may also have a greater risk of developing autism spectrum⁴ disorders⁶.

The babies in the study were born between September 1984 and July 1987 in three counties in New Jersey.

They all weighed between 0.5kg and 2kg or a maximum of about 4.4lb.

At the age of 16, 623 children were screened for risk of an autism spectrum disorder⁵ (ASD).

Of the 117 who were found to be positive in that screening, 70 were assessed again at age 21.

Eleven of that group were found to have an autism spectrum disorder.

From these results, the researchers calculated an estimated prevalence rate（流行率） of ASD of 31 out of 623 children, which is equal to 5%.

Jennifer Pinto-Martin, professor at the University of Pennsylvania School of Nursing and director of the autism centre where this research was conducted, said: "Cognitive problems in these children may mask underlying⁷ autism.

"If there is suspicion of autism or a positive screening test for ASD, parents should seek an evaluation⁸ for an ASD. Early intervention⁹ improves long-term outcome and can help these children both at school and at home."