Study co-author Dr. Jorn Olsen, chairman of epidemiology at University of California, Los Angeles, told ABC News that media coverage of the research -- scheduled to be published in the July issue of the journal Epidemiology -- has been off target.

Researchers at UCLA and Aarhus, Denmark, analyzed a survey of mothers of 13,159 children in Denmark that asked about cell phone use during pregnancy and after, as well as their child's behavior.

(We) "only briefly mentioned the possibility that maternal cell phone use, especially postnatal use, could have adverse effects on child behavior in ways having nothing at all to do with radio frequency fields," Olsen told ABC. "I don't think anyone has suggested that there is a causal mechanism."

The findings suggest pregnant women who use cell phones may increase their babies' risk of behavioral problems, but the findings are inconclusive -- for example, mothers who use their cell phones may pay less attention to their children, Olsen said.

The study also said that other confounding variables could explain behavioral changes in these children, including diet, exposure to lead paint and exposure to pollution.