Vomiting in the neonatal period is usually due to

(C). Vomiting during the 1st day of life suggests obstruction in the upper digestive tract or increased intracranial pressure. Roentgenographic studies are indicated when obstruction is suspected. Vomiting may also be a nonspecific symptom of an illness such as septicemia. It is a common manifestation of overfeeding, inexperienced feeding technique, or normal reflux and is rarely due to pyloric stenosis, milk allergy, duodenal ulcer, stress ulcer, an inborn error of metabolism (hyperammonemia, metabolic acidosis), or adrenal insufficiency.