Pregnant women using cell phones may risk having hyperactive babies with abnormal brain development, according to a new study on mice.

Researchers found that pregnant mice exposed to radiation from an active cell phone gave birth to offspring that were typically more hyperactive and anxious and had poorer memory, compared to infant mice whose mothers were not exposed to the radiation.

Researchers from Yale University, conducting the research, said that the same detrimental effects could potentially occur in people, and attributed the behavioral changes caused by abnormal fetal development of neurons in the prefrontal cortex region of the brain.

Senior researcher Yale Professor Hugh Taylor suspects that cell phones could be partly responsible for the recent rising rates of behavioral disorder like attention deficit hyperactivity disorder (ADHD).

“We have shown that behavioral problems in mice that resemble ADHD are caused by cell phone exposure in the womb,” said Taylor in a Yale news release. “The rise in behavioral disorders in human children may be in part due to fetal cellular telephone irradiation exposure.”

The research was published in the March 15 issue of the Nature publication Scientific Reports.

ADHD is a developmental behavioral disorder characterized by inattentiveness, hyperactivity and impulsivity.  The American Psychiatric Association estimates that about 3 to 7 percent of school-aged children have ADHD.

However U.S. health officials reported that approximately 9.5 percent or 5.4 million children between the ages of four to 17 years of age had been diagnosed with ADHD in 2007, which represented a 22 percent increase from 2003. 

Scientists said that the diagnosis of ADHD has increased at an average rate of about 3 percent annually since 1997, which makes the disorder “a growing public concern”.

The study consisted on 33 pregnant mice that were exposed to radiation from a silenced but active cell phone placed on at a short distance above their cage.  The phone stayed on active call for a period of 17 days, almost the whole of their 19 day pregnancy. A control group of mice were kept under the same conditions but with the phone turned off. 

More than 160 adult offspring were given a series of psychological and behavioral tests, and researchers took measurements of the electrical activity in their brain.

Tamir Aldad, another researcher involved in the study, noted that further research is needed to confirm whether the findings are applicable to human pregnancies because rodent pregnancies last only 19 days and offspring are born with a less-developed brain than human infants.

“Cell phones were used in this study to mimic potential human exposure but future research will instead use standard electromagnetic field generators to more precisely define the level of exposure,” said Aldad in a statement.

Nevertheless, the researchers said that limiting fetal cell phone radiation exposure seems warranted.

However other experts warned against applying the latest findings and assuming they were applicable to humans.

“This paper does not show any link between radiofrequency exposure and ADHD. The rate of ADHD problems has been steady for more than 20 years (any increase is due to greater recognition), so mobile phones are an unlikely cause. Taking animal studies and extrapolating directly to humans requires much more care. The exposure of the animals was very great, and the researchers' tests of animal memory should not be directly equated to human attention; different species can react differently,” Professor Eric Taylor, a child psychiatrist from the Institute of Psychiatry at King's College London told the Telegraph.

Professor Katya Rubia, a neuroscientist also from the Institute of Psychiatry even said that applying the current findings to people were “alarmist” and “unjustified” because the “motor activity in mice is not translatable to the complex human ADHD behavior”.

The researchers from the current study hope that their findings will provide greater understanding of how childhood behavior problems develop.

"The rise in behavioral disorders in developed countries may be, at least in part, due to a contribution from fetal cellular telephone radiation exposure," the researchers wrote. "Further testing is warranted in humans and non-human primates to determine if the risks are similar and to establish safe exposure limits during pregnancy."