Children exposed to complications shortly before or during birth are more likely to develop autism spectrum disorder (ASD), says a study.

The perinatal complications that had the highest association with ASD were birth asphyxia -- deprivation of oxygen during the birthing process -- and preeclampsia, a pregnancy complication characterised by high blood pressure and signs of damage to other organ systems, according to the study published in the American Journal of Perinatology.

Other perinatal complications that were associated with ASD included premature separation of the placenta from the uterus, breech/transverse fetal presentation, fetal dystocia/abnormal size or position, and a prolapsed/exposed umbilical cord.

For this study, researchers examined the electronic health records of 594,638 children born in Kaiser Permanente hospitals in Southern California between 1991 and 2009. During this time, 6,255 of these children were diagnosed with autism spectrum disorder (ASD), 37 per cent of whom experienced perinatal complications.

Researchers found that children exposed to complications during birth were at a 10 per cent increased risk of developing ASD, compared to children who did not experience perinatal complications.

That number rose to a 22 per cent increased risk of developing ASD for children exposed to complications before labour began.

The study also showed that children exposed to complications both before and during birth had a 44 per cent greater risk of developing ASD than children who did not experience perinatal complications.

"Our study suggests that children exposed to certain perinatal complications, especially birth asphyxia and preeclampsia, were more likely to be diagnosed with ASD than those who were not exposed," said study lead author Darios Getahun from Kaiser Permanente Southern California Department of Research & Evaluation.

"While there currently is no cure for ASD, early identification of children who may be at risk of developing the disorder is extremely important, as research shows that early intervention treatment services for children with ASD can greatly improve their development," Getahun noted.