Gastroesophageal reflux (GER) occurs when stomach contents come back up into the esophagus (the tube that connects the mouth to the stomach) during or after a meal. A ring of muscle at the bottom of the esophagus opens and closes to allow food to enter the stomach. This ring of muscle is called the lower esophageal sphincter (LES). This sphincter opens to release gas (burping) after meals in normal infants, children, and adults. When the sphincter opens in infants, the stomach contents often go...