When a newborn grunts during sleep, it is a common observation that often prompts concern from parents. These sounds, while sometimes surprising, are frequently a normal part of a baby’s early development. Understanding the underlying reasons for these noises can offer reassurance and help distinguish typical behaviors from those that might warrant closer attention.
Common Physiological Explanations
Newborns frequently grunt due to their still-developing digestive systems. Unlike adults who use abdominal muscles to pass stool, infants initially rely on their diaphragm, pushing against a partially closed voice box to build pressure. This process helps them learn to coordinate the muscles needed for bowel movements and gas expulsion, a stage sometimes referred to as “grunting baby syndrome”. The abdominal muscles are weak, making digestion a physical effort that can involve squirming and straining.
Babies spend a significant portion of their sleep in “active sleep,” similar to adult REM sleep. During this phase, infants are not paralyzed like adults, leading to movements and even brief eye-opening. Grunts, fusses, and occasional cries are common during active sleep as their systems process information and develop.
A newborn’s respiratory system is still maturing. Babies are primarily nose breathers for the first few months, and their nasal passages are very narrow. Even minor amounts of mucus, dried milk, or slight congestion can cause noisy breathing, snorting, or whistling sounds that might be interpreted as grunting. This immaturity means their breathing patterns can be irregular, with periods of fast breathing followed by pauses.
Distinguishing Normal Grunts from Concerning Signs
Normal newborn grunting is typically soft, rhythmic, and not accompanied by signs of distress. It does not usually disrupt their overall comfort or wakefulness. These physiological grunts are generally transient and improve as the baby matures and gains better control over their bodily functions.
Some grunting patterns or accompanying symptoms can indicate a medical concern requiring professional evaluation. Seek immediate medical attention if you observe any of the following:
Persistent grunting or grunting with every breath (signaling respiratory distress)
Flaring nostrils, where the nostrils widen with each breath
Chest retractions, which appear as the skin pulling in around the ribs or collarbone
Rapid breathing, consistently over 60 breaths per minute
Lethargy
Poor feeding
Fever
Persistent coughing
Wheezing
A bluish tint to the lips or skin (cyanosis)
Supporting Your Baby’s Comfort
Observing your baby’s grunting without immediate intervention is often the best approach, as many grunts are normal and do not require action. If grunting seems related to gas or bowel movements, gentle techniques can offer comfort. Performing “bicycle legs” by moving the baby’s legs in a cycling motion can help release trapped gas, and a gentle tummy massage in a clockwise direction can also aid digestion. Ensuring your baby is well-burped after feedings can reduce swallowed air that contributes to discomfort and grunting. Try burping every 2 to 3 ounces for bottle-fed babies or when switching breasts for breastfed infants.
For mild nasal congestion contributing to noisy breathing, a saline nasal spray followed by gentle suction with a bulb syringe can help clear the passages. Maintaining a comfortable and safe sleep environment also supports overall well-being. Always place your baby on their back on a firm, flat mattress in a crib or bassinet free of loose blankets, pillows, or soft toys.