Cellphone radiation exposure during pregnancy impacts fetal brain development and may cause hyperactivity, Yale School of Medicine researchers say.

Dr. Hugh Taylor, a medical professor and chief of Yale’s Department of Obstetrics, Gynecology and Reproductive Sciences, co-authored a recent study to probe the impact of cellphone exposure on pregnancies.

“We had pregnant mice in cages and we just simply put a cellphone on top of the cage. In half the mice, the cellphone was active and in half of the … cages the cellphone was turned off so it wasn’t transmitting a signal at all,” Taylor said.

Taylor said the researchers allowed the mice to give birth and waited until offspring were young adults before behaviours were tested.

“The mice exposed to cellphones were more active,” Taylor said. “Their memory was slightly decreased … these mice were basically bouncing off the walls and didn’t have a care in the world.”

Taylor says the study shows there is a “biological basis” to suggest cellphone exposure can impact pregnancies. He says he is encouraging patients to be cautious with devices and recommends pregnant women hold phones away from the body.

Cellphone manufacturers, including Blackberry and Apple, also say consumers should keep devices away from the body due to potential safety risks but these warnings often go unnoticed because they are featured in device manuals.

Taylor is slated to join other global researchers on Monday for a panel discussion about the impact cellphone exposure may have on pregnancies. The panel has been organized by Dr. Devra Davis, who runs the non-profit organization Environmental Health Trust.

Davis’ organization has been pushing governments around the world to take action on cellphone safety.

“While it may be legal for companies to show advertisements of phones being used in ways that are not recommended, it is not ethical,” she said. “When they sell phones to people, and they tell them in fine print to not use them next to the body, and then all their advertisements show them using cellphones exactly next to the body … I think that is really a profound disconnect that people ought to be aware of.”

The world now has almost as many cellphone subscriptions as inhabitants, according to recent numbers published by the UN telecom agency.

In 2011, the World Health Organization’s cancer arm said cellphones could cause cancer and called for more research.

Some other countries around the world, including France, have banned companies from advertising cellphones to children due to the possible risks.

Health Canada has recommended that parents should encourage youth under 18 to cap mobile phone use, but the federal government says it does not intend to bar companies from advertising products to children.

Health Canada says Canadians can use headsets and slash the length of calls in order to reduce radiation exposure.