Another obesity-linked health risk?

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More than one-third of U.S. women of child-bearing age are obese. Meanwhile, according to recent government reports, the diagnosis rate for autism in this country has increased by 78 percent in the past decade. Several recent studies have examined whether there might be a link between the two trends, and the latest of these, released online Monday in the journal Pediatrics, has found that, compared to normal-weight women, obese women were 67 percent more likely to have an autistic child.

The study, co-authored by a biostatistician at the University of California, Davis, involved over 1,000 children in California, ages two to five. In this case-control study, the authors selected nearly 700 children who had autism or another developmental delay, and compared their mothers histories to those of 315 who did not have any apparent developmental disorder. The health of the mother was determined via medical records or a structured interview. Ultimately, the researchers found the strongest link between obesity and autism-related disorders. The results suggest that women who are obese during pregnancy face a one in 53 chance of having a child with autism spectrum disorder, compared to the 1 in 88 chance among the general population.

Although researchers aren't sure how a mother's obesity could affect fetal development, they posited several theories related to metabolic changes and inflammation; thus far, however, none of these are well-supported by evidence.

As ACSH's Dr. Gilbert Ross points out, in a case-control study such as this one, a 67 percent increase is not very significant especially when there are so many confounding factors. Aside from basic knowledge of the mother's health, notes Dr. Ross, researchers had no information about the mothers actual metabolic states during pregnancy, nor about their diets and other habits during pregnancy that might have influenced fetal development.

"It's not to say that women shouldn't strive for a healthy weight before becoming pregnant," says ACSH's Dr. Elizabeth Whelan. "That's better for both mother and child, overall. However, to pinpoint obesity as a cause of autism, when there are clearly so many confounding factors in this study, is a bit premature."