According to new research children born prematurely and children born with a low-birth weight are more likely to develop autism.
In a study carried out by researchers at the U.S. Centers for Disease Control and Prevention (CDC), records of children born from 1981 to 1993 in Atlanta were examined and the researchers found that the risk was especially pronounced among low birth-weight girls.
The researchers say baby girls weighing less than 2.5 kilograms, or about 5.5 pounds, had 3.5 times increased risk of autism and girls born more than seven weeks early had a 5.4 times increased risk.
It is known that babies born with low birth weights are more at risk of bleeding in the brain, lungs that are more vulnerable to collapse, heart problems and vision loss.
However boys born with low birth weight or prematurely did not appear to have a significant difference in their risk of being autistic.
For the study 565 children with autism were paired to normal children born in the same year and the researchers found there was double the risk for developing autism in babies born prematurely, and a fivefold increased risk in girls born early.
Autism is a communication disorder that affects social interaction and learning and causes restricted and repetitive behaviour.
Symptoms usually appear after age two when the child may refuse to engage with other people, echo words and phrases, indulge in repetitive behaviour and suffer behaviour problems.
Autism and autism spectrum disorders affect roughly three to six children out of every 1,000 in varying degrees; there is no cure for the disorder but early diagnosis and intervention strategies can improve the effect of the the disorder.