I just started seeing a new chiropractor who specializes in pregnant women and infants/children. While I haven't been having many problems with heartburn this time around, she told me that adjustments to the T6 vertebra can help reduce heartburn quite a bit - and it helps many of her pregnant patients.
Last time around, I did a lot of skim milk and smooth disolve tums (but I read that since calcium relaxes smooth muscles, you don't want to do too much tums as the uterus is also smooth muscle and can lead to l-o-n-g pushing phase... which I had... so I'm trying to avoid them this time. But man did they help!). The few times I've had it this pregnancy in the middle of the night, I have been nibbling on dried papaya... simply because I can't take antacids/dairy with my other meds that I take at night. The papaya has helped a lot!