I had heartburn so bad that my Dr. told me to take Zantac 150...its the best thing I did...might want to ask your Dr about it..
Tums are safe to take while pregnant and they have calcium to.
Not that I know of. My doctor told me to take those too. I don't get heartburn anymore, but I did at the beginning of my pregnancy. I'm sure your baby will be fine or else they would have not rescribed them to you.