How much weight a mother gains while pregnant may offer clues about autism, a new study suggests.

Researchers have identified small but significant differences in patterns of weight gain during pregnancy in cases where children were later diagnosed with autism as opposed to pregnancies resulting in typically-developing kids.

However, those behind the new study were quick to emphasize that weight gain itself may not be the cause of autism, but rather that it may be symptomatic of other issues related to the developmental disorder.

“The risk of autism spectrum disorder associated with a modest yet consistent increase in pregnancy weight gain suggests that pregnancy weight gain may serve as an important marker for autism’s underlying gestational etiology,” said Deborah Bilder, an assistant professor of psychiatry at the University of Utah who led the study which was published online this week in the journal Pediatrics.

“These findings suggest that weight gain during pregnancy is not the cause of ASD but rather may reflect an underlying process that it shares with autism spectrum disorders, such as abnormal hormone levels or inflammation,” Bilder said.

For the study, Bilder and her colleagues looked at two different groups of children living in Utah. In one case, researchers compared birth records for 128 kids diagnosed with autism to a control group of 10,920 without the developmental disorder. Then, they compared records for a separate group of 288 kids on the spectrum to those of their 493 unaffected siblings.

Though the differences were small, the researchers found that autism risk was “significantly associated” with weight gain during pregnancy in both groups studied.

Bilder said that no immediate changes are warranted for pregnant mothers.

“Pregnant women should not change their diet based on these results. Rather, this study provides one more piece for the autism puzzle that researchers are exploring,” she said.

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