Obesity, diabetes in mothers linked to developmental delays

April 9, 2012

By Elise Craig
California Health Report

For years, obesity and autism have been on the rise. Now, a new study is providing evidence that maternal metabolic conditions like obesity and diabetes may be linked to developmental delays and autism.

Obese mothers are 1.66 times as likely to have a child with autism as normal weight mothers who do not have high blood pressure or diabetes, according to the study conducted by the UC Davis MIND Institute. They are also more than twice as likely to have a child with a second developmental disorder.

The researchers also found that mothers with diabetes were 2.33 times as likely to have children with developmental delays—some form of cognitive impairment, and sometimes delays in speech and motor skills—as mothers without the disease.

Though the findings showed that mothers with diabetes had a moderately higher chance of having a child with autism than healthy mothers, the difference did not reach statistical significance. However, the autistic children of diabetic mothers were likely to be more disabled than the autistic children of healthy mothers, with greater problems with language comprehension and adaptive communication.

Children who do not have autism who were born to mothers with metabolic disorders—hypertension, obesity and diabetes— showed slight deficits in language comprehension, socialization, problems solving and other skills.

In the U.S., 60 percent of women of childbearing age are overweight, while a third are obese and almost nine percent are diabetic. Roughly one in 110 children has Autism Spectrum Disorder.

Given these statistics, the study’s results raise concerns and “may have serious public-health implications,” said Paula Krakowiak, a biostatician affiliated with the MIND Institute. “Compared to genetic research, little investment has been made into research on environmental factors which may be contributing to autism risk (as well as risk for other developmental disorders),” she added. “We hope that this study will bring more attention to the need for research and funding to investigate environmental factors in relation to developmental disorders.”

Though this early research does not prove a causal relationship between maternal metabolic disorders and developmental delays and autism, Dr. Michael Stern, a professor of biochemistry and cell biology at Rice University believes “this is one area that in my opinion people need to take very seriously. It appears that there is a consensus emerging that our new hyperinsulinemic lifestyle is a serious health issue.”

Prior research has found a relationship between material diabetes and deficits in memory, motor and language development, but few studies have examined the relationship between development and obesity, hypertension and diabetes, all of which share an underlying mechanism—insulin resistance, Krakowiak said.

Mothers with insulin resistance have trouble regulating their blood sugar, which can result in chronic exposure fetal exposure to elevated insulin levels. Increased production of insulin necessitates more oxygen, and can mean less oxygen for a fetus.

Maternal diabetes can also lead to fetal iron deficiency. Both conditions “can profoundly affect neurodevelopment in humans,” the report said.

Though the study adds new insight into potential risk factors for autism and developmental disorders, both Stern and Krakowiak agree that it’s a jumping off point for further research.

“We need to go beyond correlation and go on to causation,” Stern said. “Does maternal high blood glucose cause an incidence of autism?”

“Another question left unanswered is whether some upstream environmental factors are increasing the risk for both maternal metabolic conditions and autism independently,” Krakowiak said.

However, there is no downside to advocating healthy diets among pregnant women, said Kelly Barnhill, nutrition coordinator for the Autism Research Institute. “Whole diets make a big difference in the long run,” she said. “For all of us. In the case of a child with developmental delays and disorders, we have research that when you change their diets, you can make a difference in their delay or disorder.”

The study, “Maternal metabolic conditions and risk for autism and other neurodevelopmental disorders,” was published today in Pediatrics, the journal of the American Academy of Pediatrics.

Researchers affiliated with the MIND Institute conducted the study using data from the ongoing, population-based control study, Childhood Autism Risks from Genetics and the Environment (CHARGE). They relied on medical records, birth files and medical questionnaires for information. Though, the report notes researchers only had medical records for just over half of participants, and self-provided data can be inaccurate, “in the 58 percent for whom medical records were available, the two sources were in good agreement.”

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