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As parents, we’ll move mountains for our little ones. From scheduling check-ups to planning balanced meals, setting them up for a healthy future is always a priority. But the gut microbiome is one aspect of their health that is often overlooked.
Every year, though, more parents learn how vital a balanced gut is for their baby’s development. Tiny Health’s Maturation Index is a powerful new tool that calculates your child’s gut microbiome age and tracks how their gut is developing over this crucial time.
From routine testing to actionable insights, this guide offers practical ways to support your baby’s gut health and help them thrive.
Why testing is key to understanding the gut microbiome
Your baby’s gut microbiome plays a key role in their health, from aiding digestion and nutrient absorption to immunity and brain development. It also produces mood-regulating chemicals and short-chain fatty acids, which support the nervous system and help control inflammation [1], [2].
Research shows that the foundation for a healthy gut is set during the first 1,000 days of life, making this an essential time to test and support your baby’s development.
When this ecosystem thrives, it helps reduce the microbiome risk of atopic march, a group of immune-related conditions including eczema, allergies, and asthma. It may also help reduce the microbiome-related risk of other conditions like Type 1 diabetes and obesity.
What’s a Maturation Index, and why does it matter?
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The Maturation Index uses a predictive model to calculate "microbiome age" and compares it to the range expected for their actual age. This helps you understand if their gut development is on track or if adjustments might support optimal growth. It uses key factors like microbial diversity, specific bacteria, and bacterial genes to calculate valuable insights into your baby’s gut health.
Gut maturation refers to the natural development of your baby’s microbiome during early childhood. Ideally, baby gut maturation is low in the early days and steadily increases until it reaches adult-like maturity around 3-5 years of age.
Early life microbiome maturation is shaped by many things, including:
- Birth method (vaginal or C-section)
- Feeding practices (breastfeeding, formula, or both)
- Environmental exposure (like siblings, pets, and outdoor play)
- Antibiotic use, which can disrupt the gut balance
In the first year of life, your baby’s gut microbiome forms quickly and plays a key role in developing their digestive and immune system organ [3], [4]. During this time, their gut learns to handle everything it encounters—nutrients, environmental particles, and friendly and disruptive microbes.
Ideally, gut development and microbiome maturity progress in sync. But without the right balance of microbes at key times, your baby’s gut development may be accelerated, delayed, or disrupted [5]. Emerging research suggests that rapid or out-of-sync maturation may increase the risk of your baby developing:
- Increased body mass index (BMI) or obesity [6]–[8]
- Infections [9]
- Type 1 diabetes [10], [11]
- Asthma [12]
- Atopic dermatitis, or eczema [13]
One way to protect and nurture your baby’s microbiome is to keep it from maturing too quickly [14].
How breastfeeding shapes gut development
Breastmilk contains unique sugars with important roles. Lactose, the main sugar, aids in calcium absorption. Human milk oligosaccharides (HMOs) feed beneficial gut bacteria like Bifidobacterium, which protect the gut from harmful microbes and support immune and metabolic development [15], [16].
Bifidobacterium thrives on HMOs, giving it an advantage over other bacteria. It keeps the gut less diverse, which is ideal for infants. Plus, as it colonizes, it creates acids that block harmful bacteria.
Breastfeeding keeps Bifidobacterium levels high during the first six months, which is key since low levels are linked to asthma, obesity, and autoimmune diseases [17], [18].
Tracking gut maturation: what’s expected at each stage?
Your baby’s gut microbiome grows quickly in the early years. Knowing what’s typical at each stage can help you support their health. Here’s a guide on what to look for and how to care for their gut as they grow.
Babies 0-6 Months (Milk Lover)
A low or typical Maturation Index is ideal, and breastfeeding plays a big role in building a healthy gut. Breastmilk provides essential nutrients like carbohydrates, fats, and proteins that support your baby’s digestion and immune system [19]-[22]. It also contains a natural mix of probiotics and prebiotics that helps build a stable, balanced gut microbiome.
If you’re formula feeding, look for options that include prebiotics like HMOs to support beneficial bacteria. Even partial breastfeeding alongside formula can benefit your baby’s gut health. Research shows that breastmilk suppresses gut maturation in formula-fed babies [10].
A higher Maturation Index at this age may increase the risk of conditions like obesity, eczema, and asthma later in life. In addition to formula feeding, introducing solid foods earlier than recommended may contribute to a higher index.
Babies 6-12 Months (Baby on the Move/Solid Adventurer)
Introducing solids marks a pivotal time in your baby’s gut and immune development. At around 6 months, as your little one transitions from a milk-based diet to one with a wide variety of foods, you’ll see a shift in their gut microbes. Still, breastfeeding is important because it supports good bacteria and gut health [10].
Solid food helps shape which microbes flourish and which do not. Bifidobacterium remains a key player in your baby’s gut during this stage. Your baby’s gut begins a natural shift as Bifidobacterium makes room for other beneficial species. A typical Maturation Index during this stage supports a healthy immune system and reduces the risks of asthma, eczema, and food allergies [12].
Adding new foods, especially dietary fibers, helps the microbiome mature and encourages the growth of beneficial bacteria that support overall development.
Toddlers 12-18 Months (Confident Eater)
If your toddler is still breastfeeding and has a low Maturation Index, there are several actions you can take to support their gut health during this stage. Focus on adding a variety of nutrient-rich solids to their diet to help their gut adapt to new foods and promote digestion. Cooked vegetables, whole grains, and fruits can help support their gut diversity.
Breastfeeding continues to provide unique benefits, including supporting the growth of beneficial Bifidobacteria, which can help maintain a balanced microbiome and contribute to a lower Maturation Index. Based on these results, we recommend continuing breastfeeding, as it offers benefits beyond the Maturation Index and can help prepare their gut for future developmental stages.
This period is also an excellent time to expose your toddler to a broader variety of foods and textures to encourage gut diversity. Creating balanced meals with a mix of proteins, healthy fats, and fibers helps lay the foundation for long-term gut health.
Toddlers 2-3 Years (Energetic Toddler)
For toddlers ages 2 to 3 years, it’s great if their Maturation Index is in the typical range, but don’t worry—a higher index can still be perfectly normal. You can support your toddler’s gut health by including a mix of fruits, veggies, whole grains, and fermented foods like yogurt or kefir in their meals. This will help their microbiome grow and stay balanced.
Letting your little one play with pets and spend time outdoors is a simple way to expose them to helpful microbes that boost gut diversity. These everyday habits support a healthy gut and contribute to their overall development.
If your baby’s gut health test shows a Maturation Index outside the typical range, remember that their gut is highly adaptable. Even small changes can lead to noticeable improvements.
A microbiome specialist can guide you through a personalized plan, reviewing your diet, lifestyle, and supplement use (too many probiotics can slow maturation).
Stages of maturation
The link between eczema and gut maturation
Eczema appears on the skin, but its roots are often found in the gut. This connection, called the gut-skin axis, highlights how the gut microbiome, gut barrier, and immune cells work together. Simply put, what’s happening in your child’s gut may influence how their skin reacts to environmental triggers and microbes.
Gut maturation is a crucial part of this process. If the gut microbiome matures too quickly, too slowly, or is out of balance, it can disrupt the gut’s communication with the immune system. This imbalance can make your child’s skin more reactive to triggers, increasing the risk of eczema [21].
A Baby Gut Health Test helps reveal imbalances, providing valuable insights to support your child’s gut and skin health. Your action plan may include exposing your child to diverse environments, like farms, to help strengthen their gut microbiome, support immune development, and help reduce the risk of microbiome-related conditions like asthma [23].
The benefits of routine gut health testing
The early years bring many changes; your baby’s gut adjusts to every shift in their routine and environment. Routine microbiome testing offers insights beyond regular pediatric visits, giving you a unique look into the microbial community in your little one's gut. Our Baby Gut Health Test helps you:
- Check their gut maturation age: See if their microbiome is developing too quickly, too slowly, or just right.
- Spot imbalances early: Identify disruptions caused by antibiotics and dietary changes —like starting on solids—before they lead to bigger issues.
- Support microbiome diversity: A diverse microbiome (at the right time in their development) is linked to better health outcomes and resilience against microbiome-related illness.
- Take proactive steps: Research shows that microbiome-related issues may be preventable and reversible if caught in time.
Routine gut health testing offers valuable insights into your baby’s gut development while connecting you with a microbiome specialist for one-on-one support. The test identifies strengths, highlights areas needing attention, and provides a personalized plan with steps like adding probiotics or adjusting their diet. You can also learn your baby’s gut type to better understand their development during the first year.
Support and track your baby’s gut over time
Routine microbiome testing keeps you in the know about your child’s gut health as they grow. Retesting during key milestones—like starting solids or after antibiotics—shows how their microbiome is adapting and thriving. Or, when it needs some extra support. These regular check-ins empower you to make small, meaningful changes that support healthy gut development.
For infants, we recommend testing 3-4 times during the first year if your budget allows since it’s such a crucial period for gut development. Milestones like starting solid foods and weaning from breastmilk are good opportunities to check in. Once they turn 1—and for adults too—testing every six months is ideal, though even once a year can make a difference.
Big life changes, like illness, new medications, or starting a new diet, are also good times to check in and see how their gut is adjusting. If antibiotics are prescribed, try sampling before starting them or wait 4-6 weeks after finishing to find out which species of bacteria need extra support.
With the Tiny+ Baby Membership, you can access regular testing, expert guidance, and personalized recommendations tailored to your baby’s unique needs.
