Did you know cavities are contagious?

Did You Know Your Baby’s Mouth Starts Out Sterile?

Before birth, a baby’s mouth and gut are completely sterile—no bacteria at all. But that changes quickly after delivery.

If a baby is born vaginally, their first dose of beneficial bacteria comes from mom during birth, which helps build their oral and gut microbiome. Breastmilk then continues to nourish and strengthen that microbiome.

Babies born via C-section don’t pass through the birth canal, so their microbiome is seeded mostly through breastfeeding—which is why breastmilk is especially important for C-section babies.

As babies grow, their oral microbiome (the community of bacteria in the mouth) continues to develop through diet and everyday exposure. This begins a natural process of colonization by good bacteria. One of the first friendly microbes to show up is Streptococcus salivarius—a true pioneer species!

By the end of the first year, more bacteria join in—like Streptococcus, Lactobacillus, and Actinomyces. Once teeth start to erupt, even more complex bacteria find a home, and different areas of the mouth—like grooves in the molars and the gum line—become spots where microbes settle and grow.

Interestingly, as we age and eventually lose teeth, the oral microbiome starts to resemble that of a toothless infant again. Full circle!

So what can you do to support your oral microbiome?

We want a balanced ecosystem of bacteria in the mouth—good and bad in harmony. Here's how you can help:

✅ Support the growth of good bacteria (commensals)
✅ Reduce harmful/pathogenic bacteria through mindful habits and diet
✅ Increase nitric oxide (through nose breathing and nitrate-rich foods) to support oral health

🍼 One more thing for parents:
Kissing babies on the mouth or sharing utensils can transfer your oral bacteria—good and bad—to your child. Something to think about when building their foundation for lifelong health!

Until next time,
Dr. Norma Cortez
Your Biological Airway Dentist