While uncertainty surrounds the causes of autism spectrum disorder, there is growing evidence that the risk of the condition could be determined by factors before birth. A new study has added to the debate, finding that maternal obesity and diabetes could increase the risk of the disorder.
The study, conducted by researchers from the Johns Hopkins Bloomberg School of Public Health, found that children born to women with a combination of obesity and diabetes were four times more likely to develop autism than those born to women of a healthy weight without diabetes. The team’s findings are published in Pediatrics.
“We have long known that obesity and diabetes aren’t good for mothers’ own health,” states study leader Dr. Xiaobin Wang. “Now we have further evidence that these conditions also impact the long-term neural development of their children.”
According to the Centers for Disease Control and Prevention (CDC), around 1 in 68 children are diagnosed with autism spectrum disorder (ASD).
The number of children in which the disorder has been identified has risen greatly over the past two decades; in 2000, around 1 in 150 children had been identified with the condition. Experts are unsure as to whether this increase is due to increased prevalence or merely improved methods of diagnosis.
In 2011, a meta-analysis of forty studies assessed the association between perinatal and neonatal factors and ASD risk, concluding that there was “some evidence to suggest that exposure to a broad class of conditions reflecting general compromises to perinatal and neonatal health may increase the risk.”
For the new study, Dr. Wang and her colleagues analyzed data for 2,734 mother-child pairs recruited at birth at the Boston Medical Center between 1998 and 2014.
The assessed data included maternal pre-pregnancy weight and diabetes incidence, including gestational diabetes. The children were followed up from birth with postnatal study visits and medical record examination.
During the follow-up period, the researchers identified 102 children with ASD. Those whose mothers were obese and had pre-conception diabetes were four times as likely to develop ASD compared with those whose mothers had a healthy weight and did not have diabetes.
The children of obese mothers who developed gestational diabetes were also significantly more likely to develop ASD.
“Our research highlights that the risk for autism begins in utero,” concludes co-author M. Daniele Fallin. “It’s important for us to now try to figure out what is it about the combination of obesity and diabetes that is potentially contributing to sub-optimal fetal health.”
Fallin explained to Medical News Today that there are a number of hypotheses as to why maternal obesity and diabetes might increase the risk of ASD in children, due to the fact that obesity and diabetes can cause both stress and inflammation:
“The hypothesis is that maternal stress in pregnancy may disrupt both the mother and fetus immune systems, and there are emerging theories about how disrupted immune systems and inflammation can be harmful to neurodevelopment and create risk for autism specifically.”
Another hypothesis for which evidence is building is that maternal folate supplementation could have a protective effect against autism. “Obesity is related to lower uptake of folate which could limit the protective effects of folate on autism risk,” she added.
- People with ASD often have issues with non-verbal communication and social interactions
- ASD is more common among boys than among girls
- If one identical twin has ASD, the other will be affected 36-95% of the time.
As the study is an observational one, no hypotheses can be verified. However, the results suggest that these are areas of research that deserve further investigation.
Fallin told Medical News Today that the team wants to understand what it is about obesity and diabetes that contributes to sub-optimal fetal brain development, as well as how interventions into the health of expectant mothers could improve child health outcomes such as ASD risk.
“We hope to do more molecular biomarker studies in our own cohort and also to partner with colleagues in animal modeling and other fields of neuroscience to understand these mechanisms,” she said.
“We would also love to partner with prevention scientists to learn more about how to enhance and evaluate efforts focused on promotion of health among pregnant women and women of childbearing age.”
Recently, MNT reported on research published in Scientific Reports that showed a strong relationship between a specific gene, autism and a disorder known as 22q11.2 deletion syndrome.