Doctors and researchers from Boston to Sydney are sounding the alarm on the potential risks of using wireless devices during pregnancy, calling for a closer look at technology they say could have serious long-term consequences for ?unborn babies.

More than 100 signatures appear on the notice issued yesterday by The BabySafe Project, a joint initiative of two environmental health non-profit organizations, urging pregnant women to reduce their exposure to wireless radiation emitted by products like cellphones and ?Wi-Fi routers.

“The basic reality is, we don’t know the consequences,” said Dr. Aviva Romm, one of the doctors who signed the warning and specializes in obstetrics in Western Massachusetts. “While pregnant women can’t avoid these things entirely because we’re living in a sea of it, they can minimize it.”

To date, there is no concrete evidence that wireless radiation has negative health consequences. But, Romm said, there has been research alluding to potential effects. A 2012 study out of Yale University School of Medicine showed that unborn mice exposed to cellphone radiation had impaired memory function and were more hyperactive than mice who were not exposed.

Because of the fetus’ size — and the delicate wiring of its nervous system just forming — the risks are heightened, Romm said.

“The fetus is exposed at a much higher level than adults because they’re so small,” said Romm, who went to Yale for medical school. “They’re laying down the architecture for their entire nervous system. Anything that affects it during fetal development can have implications.”

The group of doctors suggests pregnant women avoid carrying their cellphones on or near their bodies, and use their smartphones on a speaker setting or with an air tube headset.

They also recommend unplugging at-home Wi-Fi routers before bed.

But many doctors say there is little reason for concern, given the lack of evidence to support the fear.

“I don’t think we have any evidence to suggest that cellphones and wireless technologies are harmful, so I’m not sure how you’d take a leap and say it would harm the fetus,” said Dr. Leslie Kerzner, associate medical director of the special care nursery at Massachusetts General Hospital.

Walking down the street, she said, expectant mothers encounter radiation on a regular basis.

“The concept that there may be concern because the baby’s brain is rapidly dividing and growing, I understand,” she said. “But we haven’t seen any increased incidence of anomalies. I think someone is probably jumping the gun on this.”