If sucralfate is being used, it should be taken one-half hour before or after doses of antacids or alginic acid/antacid for maximal effect. (Sucralfate acts by coating and protecting the lining of the esophagus and stomach and is more effective in an acidic environment.) A small study in pregnant women has shown sucralfate to be successful in relieving heartburn. Further, studies in animals have not shown effects of sucralfate on the fetus.

Some antacids, alginic acid/antacid, and sucralfate contain aluminum, and small amounts of aluminum are absorbed into the body. However, the extra aluminum does not accumulate in the body unless there is impairment in the function of the kidneys, which normally excrete the excess aluminum. Therefore, absorption of aluminum probably does not represent a problem for the fetus unless the mother has kidney impairment.

Theoretically, magnesium-containing antacids could slow labor. (Intravenous magnesium has been used therapeutically to slow labor that is progressing too rapidly.) This potential problem, however, would only apply to magnesium-containing antacids taken just prior to labor and is not of concern earlier in pregnancy.

Antacids may interfere with iron absorption, and iron is important for the growing fetus. Nevertheless, pregnant women usually receive supplemental iron and a slight decrease in iron absorption (considering the use of supplements) should not result in a deficiency of iron. Moreover, insufficient iron intake or absorption is easily detected in blood tests as iron deficiency anemia.

If antacids, alginic acid/antacid, and sucralfate are not effective in controlling heartburn, probably the safest absorbed drugs that can be given are the H2 antagonists, specifically, cimetidine (Tagamet), ranitidine (Zantac), and famotidine (Pepcid). Although there are no studies in pregnant women, animal studies have shown no effects on the fetuses of pregnant animals. Nizatidine (Axid) should not be used because effects on the fetuses of animals have been shown, although at much greater doses than those used in humans.

Proton pump inhibitors are similar to the H2 antagonists with respect to their safety. Lansoprazole (Prevacid), rabeprazole (Aciphex), pantoprazole (Protonix), and esomeprazole (Nexium) have been shown to be safe when tested in pregnant animals, but because they are newer, experience with them is less than with the H2 antagonists. They should be used only when H2 antagonists in normal doses fail to control heartburn. Omeprazole (Cimetidine, Zegerid) probably should be avoided since although there are no studies in pregnant women showing problems, it has been shown to have effects on the fetuses of animals at very high doses in some studies.

Concerns about the use of H2 antagonists and proton pump inhibitors are greatest during the first trimester when small drug-induced alterations in fetal development can result in major abnormalities at birth. Concerns are less during the second trimester and even less during the third trimester when most critical development of the fetus already has taken place.

Metoclopramide (Reglan) is used infrequently in treating GERD. Effects on the fetuses in animals has not been demonstrated and it can be used in pregnancy. Because of its neurologic side effects, however, it should be the drug of last resort.