The Scientific Reason Your Baby Makes Those Bubbles When They Sleep

Parenthood is weird, and the sheer strangeness of it all is made all the more obvious by the fact that you can stare at a baby's face for hours, completely content. Every slight facial expression is riveting. Sometimes you're convinced you'll explode from all the cuteness. And then your baby does something strange and you're just at a loss — like that bubble thing. Honestly, why does a newborn spit bubbles while sleeping? Turns out, it's pretty normal.

When we're talking about blowing bubbles, we don't mean the kind that come out of jar with a cute wand. Some people refer to it as a frothy substance that comes out of their baby's mouth. Others say it looks like spit in the corners of their baby's mouth. The one thing these descriptions have in common is a lovely thing called saliva (so, no, it is not caused by soapy milk). But what does it mean exactly when a newborn sleeps with a foamy mouth?

Why do newborns blow bubbles while sleeping?

If your 2-week old baby spits bubbles while sleeping, it isn’t typically a cause for alarm. In fact, it’s usually a result of gravity. “When babies sleep on their backs, saliva will usually go down the back of their throats and then be swallowed,” Dr. Jessica Madden, M.D., FAAP, IBCLC, founder of Primrose Newborn Care, tells Romper. “When they are sleeping on their stomach or side, saliva can easily pool and escape through their mouths. This is the same reason that some older children and adults drool when they sleep (including me).”

Blowing bubbles is also actually a healthy part of development for many babies. “This is a normal part of oral-motor function development that occurs between 3 and 6 months of age,” Madden says. “Drooling is also associated with teething, and many babies get their first tooth around 6 months or so.” Of course, the bubbles your baby makes while they are sleeping are likely not meant to communicate anything to you, at least on a conscious level.

So long as it’s not a massive amount of spit, drooling while sleeping just shows that your baby is developing. “Babies are born with salivary glands, but they do not start to rapidly develop until they are between 3 and 6 months old,” Madden explains. “So babies make small amounts of saliva after birth, but not copious amounts until they are at least 2 to 3 months old.”

In short, the increased saliva that begins appearing around the 2-month mark is the reason your baby can make those bubbles in the first place. Your baby is also experimenting with new facial movements and new motor skills, essentially putting that saliva to work. If the bubble-blowing during sleep isn't waking your baby up, then the only downside to it all is your picture-perfect photo op being a little more, well, foamy and bubbly looking.

Can newborns have excessive saliva bubbles?

Drooling and making spit bubbles while sleeping is very normal, for the most part. However, if the drooling seems excessive, or if your baby appears to be ill, it is best to check with your child's doctor to rule out something else. “Lots of drooling is not normal during the newborn period,” Madden says. “Any newborn or young infant (less than 2 months old) with a lot of drooling needs to be evaluated to make sure they do not have a problem with swallowing or their esophagus.”

Another cause of increased drooling, especially as your baby gets older, is a common cold. “Older infants may start to sleep with their mouths open and drool more when they are asleep if they have nasal obstruction (i.e. from mucus with a cold virus),” Madden says. “This should improve as they recover from having a cold.”

Still, precautions should be taken if you notice a major increase in saliva by your baby at any age. “A sudden onset of excessive drooling should be evaluated at any age to make sure there is not a problem with something blocking the throat, such as a foreign body, or an infection of the tonsils or epiglottis,” Madden says.

All in all, drooling is incredibly common — at all ages, of course, but especially for a developing newborn. As with all concerns, though, if you have questions about your baby’s health, definitely reach out to pediatrician for medical advice.

Expert:

Dr. Jessica Madden, M.D., FAAP, IBCLC, founder of Primrose Newborn Care