About one-third to one-half of pregnant women experience heartburn. In the first trimester, this is caused by hormonal changes that can weaken the esophageal sphincter. In the last trimester, it is mainly caused by increasing pressure on the stomach from the fetus. Antacids (without sodium bicarbonate) are a good first option. The next step is an H-2 blocker, along with lifestyle modification, especially elevating the upper torso when in bed. If symptoms persist, a PPI can be tried. Clinical data on the use of PPIs during pregnancy are limited, though there are no known risks, according to the Medical Letter. Pregnant women should consult a doctor about any medications they take.