Reflux, or regurgitation, is common in infants and peaks between 3-4 months of age. GER sometimes goes unnoticed, as the liquid remains in the lower food pipe, or the liquid is regurgitated and vomited. This sequence occurs in all people, but it happens more frequently in infants under the age of 1 year. If the muscle does not entirely close, liquid flows back into the food pipe from the stomach.
This muscle relaxes to let food into the stomach and contracts to stop food and acid passing back up into the food pipe. There is a muscle at the lower end of the food pipe called the lower esophageal sphincter. Share on Pinterest This diagram shows how acid reflux occurs with GERD.