Understanding Your Baby’s Gut
This space is for you. The Infant Microbiome Institute helps parents understand what’s happening in their baby’s gut—how feeding, birth, antibiotics, and everyday choices can shape digestion, stools, rashes, and overall health. Our goal is to make the science feel calm and clear, not overwhelming.
We share general education, not personal medical advice. Always partner with your child’s own clinician for decisions about care.
What You’ll Find Here
Newborn Gut Basics
How the infant microbiome develops in the first months of life, and why it’s normal for digestion and stools to change as your baby grows.
Feeding & Formula Choices
How breastfeeding, pumped milk, donor milk, and formula each support the gut in different ways—plus things to consider when choosing or switching formula.
Symptoms: “Is this Normal?”
Gentle guidance on common concerns: gas, reflux, spit-up, diapers, rashes, and when it’s time to call your pediatric team.
Newborn Gut Basics
In the first months of life, your baby’s gut is changing rapidly. Bacteria, viruses, and other microbes are moving in, sorting themselves out, and “training” your baby’s immune system. During this time, digestion and stools can look very different from week to week—and that’s often normal.
Factors like birth mode, early antibiotics, feeding type, and environment all play a role. IMI focuses on helping you understand these factors so you can worry less about every single diaper and focus more on the big picture.
- It’s normal for stool color and texture to change.
- Most gas and grunting are part of a maturing gut.
- Patterns matter more than a single diaper or single day.
Learn More in Microbiome 101 ->
Feeding & Formula: Supporting the Gut
There is no one “perfect” way to feed every baby. Breast milk, pumped milk, donor milk, and formula are all tools that can support growth and gut development. What matters most is a fed baby, a supported caregiver, and choices that make sense for your family and medical situation.
IMI explains how different feeding options interact with the infant microbiome—human milk components, prebiotics, probiotics, and formula ingredients—so you can understand the “why” behind the guidance you hear.
We don’t partner with formula companies or accept sponsorship that could influence our educational content.
Learn more about Feeding & Formula Science→
“Is this Normal?’ vs When to Call Your Pediatrician
Almost every parent wonders if their baby’s gas, spit-up, crying, stool color, or rashes are normal. Many of these changes are part of a maturing gut and immune system—but sometimes they’re a sign that your baby needs to be seen.
Often Normal (but always ask if you’re unsure):
- Soft stools that vary from mustard-yellow to green
- Grunting, squirming, or passing gas with effort
- Small amounts of spit-up in a growing, comfortable baby
- Mild, non-oozing rashes that come and go
Call Your Pediatric Provider Urgently if:
- Your baby seems very unwell, unusually sleepy, or hard to wake
- There is blood in vomit or stool (more than a tiny streak)
- Vomit is green, or your baby is vomiting forcefully every time
- Your baby has signs of trouble breathing or dehydration
This list is not complete and doesn’t replace medical advice. If something feels “off” to you, trust your instincts and contact your pediatric team.
See Our “What’s Normal and When to Call” section -> (Microbiome 101)
Using IMI Alongside Your Pediatric Team
IMI is designed to support, not replace, your relationship with your baby’s clinicians. Our guides can help you understand the language of microbiome research and bring clearer questions to visits.
If you find an article or infographic that feels helpful, you can share it at appointments as a starting point for discussion. Your pediatric team knows your baby’s full story; IMI helps with the background science.
Not sure where to start? Visit Microbiome 101 for a gentle introduction, or explore our Parents guides by topic.