Acid reflux occurs when the contents of the stomach are refluxed into the esophagus. It’s very common in infants and most often happens after a feeding. Although the exact cause is unknown, there are several factors that can contribute to acid reflux.
Immature Lower Esophageal Sphincter
The lower esophageal sphincter (LES) is a ring of muscle at the bottom of the esophagus that opens to allow food into the stomach and closes to keep it there. This muscle isn't fully matured in infants. When the LES opens, the contents of the stomach can flow back into the esophagus, causing the infant to spit up or vomit.
This is very common and does not usually cause other symptoms. However, constant regurgitation from acid reflux can sometimes cause damage to the esophageal lining. This is much less common. If it causes symptoms such as poor weight gain, it may then be called gastroesophageal reflux disease, or GERD.
Short or Narrow Esophagus
Refluxed stomach contents have a shorter distance to travel if the esophagus is shorter than normal. And if the esophagus is narrower than normal, the lining might more easily become irritated.
Changing the foods your infant eats may help reduce the chances of acid reflux. And if you breast-feed, making changes to your diet might help your infant.
Certain foods may be causing acid reflux, depending on your infant's age. For example, citrus fruits and tomato products increase acid production in the stomach. Foods like chocolate, peppermint, and high-fat foods can keep the LES open longer, causing the contents of the stomach to reflux.
Gastroparesis (Delayed Emptying of the Stomach)
Gastroparesis is a disorder that causes the stomach to take too long to empty. The stomach normally contracts to move food down into the small intestine for digestion. However, stomach muscles don’t work properly if there is damage to the vagus nerve because this nerve controls the movement of food from the stomach through the digestive tract. In gastroparesis, the stomach contents remain in the stomach longer than they’re supposed to, encouraging reflux. It’s rare in healthy infants.
A hiatal hernia is a condition in which part of the stomach sticks through an opening in the diaphragm. A small hiatal hernia doesn’t cause problems, but a larger one can cause acid reflux and heartburn.
Hiatal hernias are very common, especially in people over the age of 50, but they are rare in infants. However, the causes are unknown. A hiatal hernia in children is usually congenital (present at birth) and may cause gastric acid to reflux from the stomach into the esophagus.
Positioning — especially during and after feeding — is a frequently overlooked cause of acid reflux in infants. A horizontal position makes it easier for the stomach contents to reflux into the esophagus. Simply keeping your infant in an upright position while you’re feeding them and for 20 to 30 minutes afterward may reduce acid reflux.
This also applies to sleeping positions. It’s recommended that babies sleep on their backs to reduce the risk of sudden infant death syndrome (SIDS). However, babies who experience reflux may benefit from sleeping in a slightly elevated position on their left sides. This position may make it harder for the stomach contents to reflux. However, the risk of SIDS is doubled for infants sleeping on their side versus their back. Discuss the potential pros and cons with your doctor before placing your infant to sleep in any position other than on their back.
Angle of His
The angle at which the base of the esophagus joins the stomach is known as the “angle of His,” and differences in this angle may contribute to acid reflux. This angle most likely affects the ability of the LES to keep the contents of the stomach from refluxing. If the angle is too sharp or too steep, it may make it difficult to keep the stomach contents down.
Feeding your infant too much at once, either with a bottle or while breast-feeding, can cause acid reflux. Feeding your infant too frequently can also cause acid reflux. An oversupply of food can put too much pressure on the LES, which will cause your infant to spit up. That unnecessary pressure is taken off the LES and reflux decreases when you feed your infant less food more often. However, if your baby spits up often, but is otherwise happy and growing well, you may not need to change your feeding routine at all. Talk with your doctor if you have concerns that you are overfeeding your baby.
When to Call Your Child’s Doctor
Your infant will usually grow out of acid reflux. However, call your child’s doctor immediately if you notice that your child:
- isn't gaining weight
- is projectile vomiting
- has blood in their stool
- won’t eat
While it isn’t easy to determine the exact cause of acid reflux in infants, lifestyle and diet changes may help eliminate some of the factors. If the acid reflux doesn’t go away with these changes and your baby has other symptoms, a doctor may have to perform tests to rule out a gastrointestinal obstruction or other problems with the esophagus.