usually if you are having heart burn it from something that you are eating that is not agreeing with you try being concious of what you are consuming and eliminating it.

i know with my oldest i craved lemonaid -- yeah really bad idea I would have to avoid it at all costs or i would get heartburn

Actually heartburn during pregnancy has NOTHING to do with what you eat. uhh the doctor can explain why you get heartburn during pregnancy better than I can but it does have something to do with the baby pushing on your osophagusts (sp).
Talk to your doctor because they can give you zantac or the like but you have to be at least in your second trimester to take it. and the nice thing about zantac is that you can take it and nurse at the same time after baby is born. and its so much better than tums which is so gross and doesnt work very well or as long