Many people with GERD also have what's called a "hiatal hernia."
As we mentioned earlier, your esophagus passes through an opening in your diaphragm called the hiatus, which helps close off the lower esophageal sphincter. A hiatal hernia happens when a small part of your stomach and the sphincter poke up THROUGH the hiatus into your chest. This can cause the sphincter to become weak, and less able to block acid reflux.
While hiatal hernias can happen in people of all ages, they are more common in people over the age of 50. And, while most people who have hiatal hernias don't have any problems, a hiatal hernia CAN make it more likely that you'll get heartburn and possibly develop GERD.