Heartburn is a common complaint during pregnancy, affecting up to 80% of women. It is caused by the relaxation of the esophageal sphincter, a muscle that normally keeps stomach contents from flowing back into the esophagus. This relaxation can be caused by the increased levels of progesterone during pregnancy, which can also slow down digestion.
Heartburn can be uncomfortable and interfere with daily activities. It can also lead to other problems, such as esophagitis (inflammation of the esophagus) and esophageal cancer.