Obese women and those with Type 2 diabetes could be increasing their chances of having a child with autism or another development disorder, a US study suggests.
Researchers at the University of California Davis said that high glucose levels during pregnancy could affect brain development in the foetus.
The Paediatrics study looked at 1,000 children and mothers over seven years.
Diabetes UK said further research was needed.
The children in the study were aged between two and five-years-old, and were enrolled between 2003 and 2010.
Among the children whose mothers had Type 2 diabetes during their pregnancies, the study found that 9.3% of those children had autism.
And 11.6% of that group of children showed evidence of a developmental disability.
This was nearly twice as high as the 6.4% of children with these problems born to women with no metabolic conditions.
Over 20% of the mothers of children with autism or other developmental disability were obese, compared with 14% of the mothers of normally developing children.
Around 29% of the children with autism had mothers with a metabolic condition during pregnancy, such as diabetes, high blood pressure and obesity.
Nearly 35% of the children with another developmental disorder had mothers with metabolic conditions, compared to 19% of children in the control group.
The study also examined the link between hypertension and autism or developmental disorder.
When analysing children's cognitive abilities, the study found that among the children with autism, those whose mothers had diabetes did not perform as well as those whose mothers did not in tests of expressive language and communication skills.
Paula Krakowiak, from the MIND Institute at the University of California Davis, said: "Our finding that these maternal conditions may be linked with neurodevelopmental problems in children raises concerns and therefore may have serious public-health implications."
Dr Matthew Hobbs, head of research at Diabetes UK, said more research was needed to answer questions not investigated in the study.
"It is important to note that while it does show an association, it does not show that diabetes causes developmental problems.
"We continue to advise that women with diabetes should tell their diabetes health care team if they are planning to become pregnant. They can then work together to make sure they are aware of the steps they should take to help them have a healthy pregnancy."