What causes GERD and acid reflux in infants and children?

Acid reflux in infants is common. The reason for this is due to the immaturity of the muscle between the stomach and oesophagus, known as the lower oesophageal sphincter, or LES. At birth, this muscle is still a little under-formed and thus allows for stomach contents and acid to flow back upwards into, and possibly out of the mouth. In time, the LES will function properly by opening when your infant swallows and closing when the infant is not eating or drinking, keeping the stomach contents in place.

There are several factors that can contribute to acid reflux in infants, some of which cannot be avoided, these include:

• Infants being born prematurely or of low birth weight – the LES is then very premature and underdeveloped
• Infants lying flat on their backs most of the time
• Infants having an almost completely liquid diet (only breastfeeding or formula)

In some cases, acid reflux in infants and children can be the result of more severe conditions, these include:

• Food intolerances- Food allergies such as a food intolerance to cow’s milk (lactose) can sometimes be a trigger for reflux.
• Pyloric stenosis- This is when the valve between the small intestine and the stomach malfunctions, preventing the stomach contents from being emptied into the small intestine. This leads to pressure build up in the stomach which may result in vomiting and complications of reflux including, dehydration and weight loss.
• Eosinophilic oesophagitis- In some cases, a condition known as eosinophilic oesophagitis, which is when a specific white blood cell type, known as eosinophil, builds up in the lining of the oesophagus and in turn damages the oesophagus.

Conditions which impair muscle and nerve development – This leads to an impaired swallowing ability which may involve reflux (e.g. Cerebral palsy, which is a condition that appears in infancy or early childhood and affects muscle coordination and body movement).