Tums are safe to take during pregnancy. In fact, your first line of defense should probably be these chewable antacids made from calcium carbonate (sometimes just called "calcium" on the label).

Calcium is significantly important for the growth of bones and teeth, particularly during pregnancy. Although one can obtain enough calcium from food, a lot of expecting mothers find it ...

Calcium (as carbonate) 750mg; chew tabs; melon-berry flavor. <12yrs: not recommended. ≥12yrs: 2–4 chew tabs as symptoms occur; max 10 chew tabs per 24hrs. Pregnancy: max 6 chew tabs per 24hrs.