Heartburn is very common in pregnancy. Many women will experience heartburn for the first time when they are pregnant.
The high progesterone levels in pregnancy will relax the sphincter muscle in your lower esophagus and the enlarging uterus will also put pressure on your stomach, allowing stomach acid to enter the esophagus and cause heartburn.
Try to eat slowly and try to not lie down for at least an hour after you have eaten.
Avoid spicy foods. Over-the-counter antacids such as Tums® can be helpful. For more persistent cases, over-the-counter Ranitidine (Zantac®) is felt to be safe by many health care providers.