A baby sometimes regurgitates small amounts after a feeding. This is called spitting up.

What is going on in the body?

Spitting up occurs in many young infants. In some children, it may continue through the first year. The problem occurs because some of the muscles in the baby's digestive system are not yet mature.

When food is swallowed, it travels to the stomach through a long muscular tube known as the esophagus. Waves of muscle contractions propel food down the esophagus. The valve connecting the esophagus to the stomach is called the gastroesophageal sphincter. Normally, this valve closes after eating to keep food from rising back into the esophagus.

In newborns, this valve has not fully developed. That makes it easier for food to move backward, up the esophagus. Spitting up usually occurs during or shortly after feeding. Most of the time, the food rolls out of the mouth without much force. The amount that comes out is rarely more than an ounce.

It is important to distinguish spitting up from vomiting. With vomiting, larger amounts of stomach contents are forcefully expelled. Material may come out of the nose as well. Vomiting is usually a sign of an illness.

What are the causes and risks of the condition?

Premature infants may be more likely to spit up. This is because their digestive systems are not as mature at birth as those of full term infants.