Babies grunt from time to time while trying to pass stool or breathe during feedings and when recognizing and imitating sounds and voices. When a baby grunts continuously and breathing is hard and fast, it could be a sign of respiratory distress, according to WebMD.
Grunting and groaning during breathing can be detected by watching a baby's chest muscles and nostrils. Signs of respiratory distress include grunting, fast breathing, flared nostrils and rapidly contracting chest muscles, according to WebMD.
Constant grunting may indicate discomfort when passing stools or be a sign of constipation. In addition, babies with acid reflux often grunt and make noises during sleep due to discomfort, according to parenting.com. Mild reflux causes babies to spit up, as stomach acids rise to the throat. Babies often grunt or make wheezing sounds when reflux is painful because it feels similar to heartburn.
In extreme cases, grunting when breathing may be a symptom of a congenital heart defect in newborns and babies, according to Mayo Clinic. When grunting is accompanied by pale gray or blue skin color, flared nostrils, rapid breathing, and swelling in the abdomen, legs or areas around the eyes, a consultation with a physician is recommended to rule out or treat heart defects.