I have a 4 month old - she is my third baby and she gave was the only one to give me heartburn... and it was extremely rough. I actually went to the ER on Easter Sunday because it got so bad.
That said, it started out just feeling like pain radiating around my ribs. It got progressively worse - between about 31 weeks to about 36 weeks.
In the beginning my OB's office recommended the TUMS, and Maalox - neither worked at all. I also tried Zantac and it didn't work at all.
Finally, I ended up in the ER and they have me Rx protonix, which worked wonders. I had lost several pounds b/c I had to severely limit the types of foods I could eat. The baby was growing fine though, I was the one suffering! :)
I talked to a GI specialist who is a family friend about it and he said this was the same medication as over the counter Prevacid. Both of these medications are safe during pregnancy. In fact, they are class B drugs while Zantac is class C.
Anyway, I would talk to your doc about taking the Prevacid or get an Rx for the protonix. I honestly didn't know how painful heartburn could be until I experienced it myself. I feel for you. Good luck!