MIAMI (AFP) - When pregnant women develop gestational diabetes early in pregnancy, their children may face a higher risk of developing autism, researchers said Tuesday.

While the findings in the Journal of the American Medical Association (Jama) do not prove that diabetes in pregnancy causes autism, researchers said their findings highlight a link that deserves further study.

Autism is a developmental disorder that affects as many as one in 68 children in the United States, and its causes remain poorly understood.

Gestational diabetes affects nearly one in 10 women, and is a high blood sugar condition that arises in pregnant women who did not previously have diabetes.

The study spanned the electronic health records of more than 322,000 children born between 28 and 44 weeks at Kaiser Permanente Southern California medical centers between 1995 and 2009.

The children were followed for an average of five and a half years after birth.

Women who developed gestational diabetes by the 26th week of pregnancy had a 63 percent higher risk of having offspring with autism than children whose mothers did not have gestational diabetes.

After accounting for factors such as maternal age, education, race and ethnicity and household income, the increased risk of autism associated with gestational diabetes was 42 per cent.

There was no higher risk of autism in women who developed gestational diabetes later than the 26th week of pregnancy.

"The exposure of fetuses to maternal hyperglycemia may have long-lasting effects on organ development and function, but whether this can disrupt fetal brain development and heighten risk for neurobehavioral developmental disorders in offspring is less clear," said lead author Anny Xiang of the Kaiser Permanente Southern California Department of Research and Evaluation.

"Future studies should address whether early diagnosis and treatment of gestational diabetes can reduce the risk of autism."