Skip to Content

Why does baby breath smell good?

Newborn babies have a very distinct smell. Many parents report that their baby’s breath smells sweet or even pleasant. This is in stark contrast to bad adult breath, which can smell foul. So why does a newborn baby’s breath smell good? There are several reasons.

Newborn’s Diet

A major factor is a newborn’s diet. Newborns exclusively have breastmilk or formula. Breastmilk contains lactose, which is a natural sugar. It also contains probiotic bacteria from the mother which assists in the baby’s gut health and digestion. Formula tries to mimic the nutritional makeup of breastmilk and also contains lactose and probiotics.

In contrast, adults eat a wide variety of foods. Things like onions, garlic, spices, and certain proteins can cause odors in an adult’s breath. A newborn does not consume these foods yet, so their breath smells neutral if not sweet.

Oral Hygiene

Oral hygiene is another reason newborn breath smells good. Newborns do not have teeth, so they cannot get food particles stuck that would rot and cause odors. Adults also have mouths full of bacteria. The different types of bacteria in our mouths contribute to bad breath.

Newborns have not built up near the concentration of bacteria in their mouths yet. Their mouths are still very clean and neutral smelling. They have not needed intensive oral hygiene practices like brushing and flossing yet.

Tongue Appearance

A newborn’s tongue also looks different than an adult’s tongue. Newborns usually have a white tongue while adults have a pink tongue. The white color on a newborn’s tongue is due to being covered with a film of bacteria and dead skin cells. This layer has not built up yet on a newborn.

As adults, we brush our tongues to remove this film layer. When we do not brush properly, the film layer can get thicker and result in bad breath. A newborn does not have this thick white film yet, so their breath smells normal.

Lung Development

A newborn’s lungs are also still developing. The lungs continue to form alveoli and strengthen the respiratory system into childhood. Because of this, a newborn’s breath smells clean and neutral.

As we age, our respiratory systems accumulate environmental particles, bacteria, and viruses. Our lungs have to work harder to expel waste. Lingering particles or infections in an adult’s lungs can cause odors. A newborn’s underdeveloped lungs do not have waste in them yet.

Liver Function

A newborn baby’s liver is still maturing as well. One of the liver’s 500 functions is to filter blood coming from the digestive tract before it circulates through the rest of the body. The liver converts compounds into waste products that cause bad odors.

With an underdeveloped liver, newborns do not have concentrated waste products in their blood yet. Their blood remains clean and odor-free. Their breath consequently has a clean smell.

Kidney Function

A newborn’s kidneys also impact their breath smell. The kidneys filter the blood to remove wastes and extra fluid. This process keeps blood clean. The kidneys also regulate pH balance in the bloodstream. Proper pH balance stops acids from building up that cause odors.

Newborn’s kidneys are still growing, but they filter blood sufficiently to keep away odor-causing compounds. As the kidneys mature, they have an increased filtration burden that allows some smelly compounds into the bloodstream and breath.

Impact of Birth Canal

For vaginal births, a newborn’s passage through the birth canal can also impact their breath smell. The birth canal is home to various bacteria that help promote a healthy microbiome. As the baby travels through the vaginal canal, they are exposed to these bacteria.

The bacteria colonize on the newborn’s skin and in their lungs. This bacterial exposure is extremely important for the newborn’s immune system development. However, the bacteria can also lead to a slightly different or sweeter smell on the newborn’s skin and breath right after birth.

Sweat and Hormone Glands

Newborns also do not have activated sweat or hormone glands yet. In adolescence, activation of sweat and hormone glands leads to new body odors forming as we enter puberty. This includes odors in sweat, saliva, and breath.

A newborn’s inactive glands mean body odors from these sources have not developed yet. Their breath, skin, and other secretions will still smell neutral rather than strong.

Biological Instinct

There may also be an evolutionary reason that newborn breath smells good. Since a newborn relies entirely on its caregiver, a pleasant baby scent could aid bonding. Adults are biologically wired to respond positively to sweet, clean baby scents.

Seeing a sweet face is one bonding mechanism. The good smell of a newborn may also trigger an instinctual emotional response to care for the vulnerable baby. This could be why many parents report loving the smell of their newborn’s skin and breath!

When Does Baby Breath Smell Go Away?

Newborn breath will not smell sweet forever. As a baby grows and develops, their breath will start smelling more neutral or even bad at times. Here is an approximate timeline of how long a baby’s breath smells good:

  • 0-3 months – newborn breath smells sweet
  • 3-6 months – breath starts smelling more neutral
  • 6-12 months – primary teeth appear and breath smell changes
  • 1+ years – baby breath gone as diet changes

Parents should take advantage of the newborn breath smell while it lasts! Once teeth, foods, and oral bacteria build up, a baby’s breath will start resembling an adult’s breath. The sweet and innocent newborn breath is fleeting.

When to Worry

While baby breath smells pleasant for the first few months, bad odors can be a sign of health problems. Here are signs of abnormal breath to watch out for:

  • Foul, rotten, or fishy smell
  • Metallic smell
  • Smell of feces
  • Smell of acetone
  • Smell of ammonia

If a newborn has persistent bad breath with any of these odors, consult a pediatrician. It may signal a health issue like an infection, metabolic disorder, or stomach issue.


A newborn baby’s breath smells sweet and pleasing to most parents. This is due to underdeveloped organs, neutral diet, and lack of bacteria buildup in the mouth. Newborn breath smells good thanks to a combination of these factors.

However, baby breath smell changes quickly as a child develops. Diet expands, teeth erupt, and odor-causing compounds increase. The key is enjoying the short period of pleasant newborn breath while it lasts!