Spitting up (burping up) is the effortless return of swallowed formula or breast milk through the mouth or nose after feeding. Almost all infants spit up, because infants cannot sit upright during and after feedings. Also, the valve (sphincter) that separates the esophagus and stomach is immature and does not keep all of the stomach's contents in place. Spitting up gets worse when an infant eats too fast or swallows air. Spitting up usually stops between the ages of 7 months and 12 months.

Spitting up can be reduced by feeding infants before they get very hungry, burping them every 4 to 5 minutes, placing them in an upright position during and after feeding, and making certain the bottle nipple lets out only a few drops with pressure or when the bottle is upside down. Spitting up that seems to cause an infant discomfort, interferes with feeding and growth, or persists into early childhood is called gastroesophageal reflux and may require medical attention (see Gastroesophageal Reflux in Children). If the material that is spit up is green (indicating bile) or bloody or causes any coughing or choking, medical attention is needed.

Vomiting is the uncomfortable, forced throwing up of feedings. It is never normal. For a more complete discussion, see Vomiting in Infants and Children.

Vomiting in infants is most often the result of acute viral gastroenteritis. It can also be caused by infections elsewhere in the body, such as ear or urinary tract infections. Less commonly, vomiting occurs because of a serious medical disorder. Infants between the ages of 2 weeks and 4 months may rarely have forceful (projectile) vomiting after feedings because of a blockage at the stomach outlet (hypertrophic pyloric stenosis). Vomiting can also be caused by life-threatening disorders, such as meningitis, intestinal blockage, and appendicitis. These disorders usually cause severe pain, lethargy, and continuous vomiting that does not lessen with time.

Most vomiting caused by gastroenteritis stops without treatment. Giving the child fluids and electrolytes (such as sodium and chloride) from solutions available in stores or pharmacies prevents or treats dehydration. A child who is vomiting frequently may tolerate small amounts of solution given more often better than large amounts given less often. Older children can be given popsicles or gelatin, although red versions of these foods can be confused with blood if the child vomits again. A doctor should see any child who has severe abdominal pain, is unable to drink and retain fluids, has a high fever, is lethargic or acting extremely ill, vomits for more than 12 hours, vomits blood or green material (bile), or does not urinate in 8 hours. These symptoms may signal dehydration or a more severe condition.

Overfeeding is the provision of more nutrition than a child needs for healthy growth. Overfeeding occurs when children are automatically fed as a response to crying, when they are given a bottle as a distraction or activity, or when they are allowed to keep a bottle with them at all times. Overfeeding also occurs when parents reward good behavior with food or expect children to finish their food even if they are not hungry. In the short term, overfeeding causes spitting up and diarrhea. In the long term, overfed children can become obese (see Obesity in Adolescents).

Underfeeding is the provision of less nutrition than a child needs for healthy growth. It is one of many causes of failure to thrive (see Failure to Thrive) and may be related to the child or the caregiver. Underfeeding may result when a fussy or distracted infant does not sit well for feedings or has difficulty sucking or swallowing. Underfeeding can also result from improper feeding techniques and errors in formula preparation (see Formula Feeding). Poverty and poor access to nutritious food are major reasons for underfeeding. Occasionally, abusive parents and parents with mental health disorders purposely withhold food from their children.

Community social agencies (such as the Women, Infants, and Children [WIC] program—www.fns.usda.gov/wic/) can help parents purchase formula and can teach them proper techniques for formula preparation and feeding. If an infant is so far below expected weight that supervised feedings are necessary, the doctor may admit the child to a hospital for evaluation. If the parents are abusive or neglectful, Child Protective Services may be called.