Heartburn is a digestive problem that occurs when stomach acid comes into contact with the lining of the esophagus, causing irritation. Classic symptoms include an uncomfortable burning sensation in the chest and throat along with a bitter taste in the mouth. Millions of people suffer from occasional heartburn, usually following a meal or after going to bed.

If heartburn is severe or persistent, it could be a symptom of a more serious condition called gastroesophageal reflux disease, or GERD. If left untreated, GERD can contribute to a wide range of problems. Fortunately, many of these complications can be avoided with simple lifestyle changes and proper monitoring from a health-care professional. Here, a look at heartburn by the numbers:

  • 10 million: Number of American adults who suffer from heartburn every day.

  • 60 million: Number of American adults who suffer from heartburn at least once a month, according to the American College of Gastroenterology.

  • 75: Percentage of heartburn sufferers who say nighttime heartburn wakens them or prevents them from sleeping.

  • At least 3: Hours after a meal that bedtime should occur, in order to prevent nighttime heartburn, according to the National Institutes of Health (NIH).

  • More than 50: Percentage of heartburn sufferers who consider the stresses of work and home to be contributors to their symptoms, according to a survey released by the National Heartburn Alliance.

  • 94: Percentage of heartburn sufferers who can link their symptoms to specific foods.

  • 50: Percentage of pregnant women who experience heartburn or related symptoms.

  • 3: Trimester number in which heartburn is most common, due to increased pressure on the intestines and stomach from the growing uterus, according to the American Pregnancy Association.

  • 65: Percentage of Americans who are not aware that heartburn can cause serious complications if left untreated, according to the National Heartburn Alliance.

  • 10: Average length, in inches, of a normal esophagus, the tube which connects the mouth to the stomach.