Baking Soda!!

Is it safe??? Is it safe to take baking soda and water to help with Hearth Burn while pregnant?? Until last night I tought it was ok but I talked to an after hours nurse and she said No! Not to take it beacause its considered a "Category C" substance and the FDA doesn't know what affect it may have on the baby,specially during the first Trimester. So unless my OB says Yes its a Big No only Tums is ok.