I never press the phone to my head, I always use speakerphone. I would keep it away from the baby, considering the baby will have plenty of time later to use the cell phone. This little bit of radiation is not that bad for us, not nearly as bad as the sun. You can get sunburn fro the sun, but not from your phone. I would not worry too much. But yes, just to be safe, turn the phone off and or keep it at other end of the house if your mom says so, maybe she has an intuition.