May 26, 2011 (San Diego, California) — Maternal type 2 and gestational diabetes, hypertension, and obesity, which are conditions indicative of elevated insulin resistance, may be risk factors for autism and other developmental disorders, according to research presented here at the International Meeting for Autism Research (IMFAR) 10th Anniversary Meeting.
Investigators at the University of California, Davis, found women with these conditions were more likely to have a child with autism/autism spectrum disorders (ASDs) or other developmental delays (DDs) compared with women without these conditions.
The prevalence of these metabolic conditions was higher among mothers of children with ASDs or DDs than of typically developing (TD) children, said first study author, Paula Krakowiak, MS.
Maternal diabetes, in particular, was associated with slower language development in children with and without ASDs, she added.
Gestational and type 2 diabetes complicate approximately 9% of pregnancies in California. In the United States, nearly 60% of women aged 20 to 39 years are overweight, and 34% of women in that age range are considered obese. Chronic hypertension is seen in 1.1% of pregnancies.
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The prevalence of ASDs and other DDs is rising alongside these metabolic conditions, said Ms. Krakowiak. In this study, the investigators explored the relationship between maternal hypertension, diabetes, and obesity and the likelihood that a child will have an ASD or DD.
This research was part of the Childhood Autism Risks from Genetics and the Environment (CHARGE) study, a population-based, case-control study of children between 2 and 5 years of age who have ASDs or DDs and randomly selected TD controls in the same age range.
Diabetes, hypertension, and obesity were more common among mothers of children with ASDs or DDs compared with mothers of TD children.
In addition, prenatal exposure to maternal diabetes particularly was associated with greater deficits in language development among children with ASDs. This association was also seen among children without ASDs. Moreover, exposure to any metabolic condition in utero was associated with language impairment among children without ASDs, Ms. Krakowiak said.
Maternal metabolic conditions may affect fetal neuronal development in a variety of ways, she explained. Inflammation associated with diabetes, hypertension, and obesity is marked by increased maternal proinflammatory cytokine levels in the blood, including interleukin 6, which can cross the placenta and may affect fetal brain development.
Chronically elevated maternal glucose levels, which characterize diabetes, can also lead to fetal hyperinsulinemia. Consequently, this environment may accelerate fetal growth and oxygen consumption, potentially resulting in fetal brain damage if fetal hypoxia or iron deficiency ensues.
"This was a very nice paper," said Lisa Croen, PhD, senior research scientist and director of the Autism Research Program at Kaiser Permanente Northern California.
However, she noted that women with gestational and type 2 diabetes had been lumped together and questioned whether the 2 groups might have been associated with different outcomes. Dr. Croen was not involved in this research.
Mothers with gestational diabetes outnumbered the women with the type 2 form, said Ms. Krakowiak.
"I combined them because they share a similar etiology in that the underlying pathology involves insulin resistance in both conditions. Many women who have gestational diabetes go on to develop type 2 diabetes later in life."
Ms. Krakowiak and Dr. Croen have disclosed no relevant financial relationships.
International Meeting for Autism Research (IMFAR) 10th Anniversary Meeting: Abstract 131.007. Presented May 14, 2011.
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