Researchers say there may be a link between mums who develop diabetes in pregnancy and autism spectrum disorders.
They identified that children had a 63 per cent greater risk of being diagnosed with autism if they had been exposed to gestational diabetes 26 weeks into the gestation period.
They found no significant association between an increased risk in autism and pre-existing type 2 diabetes in mothers, and there was no significant risk increase in mothers diagnosed with gestational diabetes after 26 weeks.
Babies born to mothers with type 1 diabetes were not included in the study of more than 320,000 children.
No link was seen between women who had type 2 diabetes before getting pregnant and autism spectrum disorders.
Diabetes that develops in pregnancy is called gestational diabetes and should be checked for, and picked up, during routine appointments so that it can be managed or treated.
Gestational diabetes affects up to 1 in 20 pregnancies and usually goes away after the baby is born.
With untreated diabetes, blood sugar levels can be higher, and there’s some evidence this can affect organ development for a growing foetus.
What hasn’t been clear is any effect on brain development and a risk of developmental disorders.
The researchers, from the US, said: “Our results help to clarify the relationship between exposure to maternal diabetes in utero and risk of autism spectrum disorders in offspring.
“Because the association was stronger for gestational diabetes diagnosed at 26 weeks or earlier than for recognised pre-existing type 2 diabetes, we speculate that some children in [that group] may have been exposed to untreated hyperglycaemia during early critical brain developmental windows, which led to autism risk after birth.
“Pre-existing type 2 diabetes may have been treated aggressively during pregnancy, which may have reduced the effect on foetal brain development.”
Experts say more research is needed to confirm the findings and to dig deeper into the cause of the apparent link.
The increased risk was independent of maternal smoking, pre-pregnancy BMI and gestational weight gain.
Trends suggest diagnoses of autism are on the rise, and the condition is estimated to affect almost 1.1 per cent of the UK population.