Why Are So Many Babies Missing Bifidobacterium?

If you’ve started learning about infant gut health, you’ve likely heard about Bifidobacterium. It’s not just another probiotic trend — it’s a group of beneficial bacteria that babies are meant to have from birth.

In healthy infants, Bifidobacterium plays a foundational role in early development. These microbes help digest human milk, support immune system training, reduce inflammation, and influence everything from digestion to skin health and comfort. In fact, babies evolved to rely on Bifidobacterium during the first years of life, when the gut and immune system are developing most rapidly.

But today, many babies are missing these critical microbes.

Most modern babies aren’t getting the bacteria they were born to have

As seen in our My Baby Biome study (which analyzed the gut microbiomes of hundreds of U.S. infants) 90% of babies are missing one or more key strains of Bifidobacterium. Even more concerning, about one in four babies had no detectable Bifidobacterium at all.¹

This is a striking shift from what researchers see in healthy, breastfed babies from previous generations — or in more traditional communities, where Bifidobacterium still dominates the infant gut.² So what changed?

Modern life changed the infant microbiome

There isn’t a single cause. Instead, several normal, often necessary aspects of modern parenting have quietly reshaped how a baby’s gut microbiome develops.

C-sections: Cesarean deliveries are life-saving and essential for many families. But they also change how microbes are transferred from mother to baby at birth. During vaginal delivery, babies are exposed to beneficial bacteria that help seed the gut — including Bifidobacterium. When that transfer is altered, early gut colonization can look very different, especially in the first months of life.³

Antibiotics: Antibiotics protect babies from serious infections, but they also affect the developing gut microbiome. Along with harmful bacteria, antibiotics can reduce beneficial microbes like Bifidobacterium. In early life, these microbes may recover slowly — and sometimes less beneficial bacteria take their place.⁴

Feeding differences: Breast milk contains human milk oligosaccharides (HMOs) — special prebiotics that babies can’t digest themselves. Instead, HMOs are designed to feed Bifidobacterium, helping these beneficial bacteria thrive. Formula-fed or mixed-fed babies often receive less of this targeted support, though formulas with HMOs are becoming more common. Without their preferred food source, Bifidobacterium has a harder time establishing itself in the infant gut.

Modern environments: Babies today grow up in cleaner, smaller households with less community exposure. While this reduces the risk of dangerous infections, it also limits exposure to beneficial microbes that historically helped shape a healthy microbiome.

These changes weren’t mistakes — but they have consequences

None of these practices are “bad.” They reflect medical progress and modern living. But together, they’ve made it harder for babies to develop the gut microbiome they were born to have — especially during the critical early window when gut and immune health are being programmed.

And that matters. Research shows that 3 in 4 babies (76%) with low levels of healthy gut bacteria are at a higher risk of developing chronic conditions later in life, including food allergies, eczema, and asthma.¹

Supporting what modern life took away

Because modern practices aren’t going away, supporting the infant gut has become more important than ever.

That’s where Persephone’s synergistic synbiotic comes in. Designed from real infant microbiome research, Persephone helps restore Bifidobacterium using infant-specific strains paired with the exact prebiotics they evolved to eat. By supporting the gut early, we’re helping nurture calmer tummies today — and stronger immune health for years to come.

*Medical Disclaimer

The information provided on this blog is for educational purposes only and is not intended as medical advice, diagnosis, or treatment. Every baby is unique, and health decisions should always be made in partnership with a qualified healthcare professional. If you have questions or concerns about your child’s health, diet, or development, please consult your pediatrician or another trusted healthcare provider before making changes.

References:

1. Jarman, J.B., Torres, P.J., Stromberg, S. et al. Bifidobacterium deficit in United States infants drives prevalent gut dysbiosis. Commun Biol 8, 867 (2025). https://doi.org/10.1038/s42003-025-08274-7.

2. Seppo, A.E. et al. Infant gut microbiome is enriched with Bifidobacterium longum ssp. infantis in Old Order Mennonites with traditional farming lifestyle. Allergy Vol 76, 3247-3565 (2021). https://doi.org/10.1111/all.14877.

3. Inchingolo, F., et al. The Impact of Cesarean Section Delivery on Intestinal Microbiota: Mechanisms, Consequences, and Perspectives—A Systematic Review. Int. J. Mol. Sci. 2024, 25, 1055. https://doi.org/10.3390/ijms25021055. 

4. Hoskinson, C., et al. Antibiotics taken within the first year of life are linked to infant gut microbiome disruption and elevated atopic dermatitis risk. Journal of Allergy and Clinical Immunology Vol 154, 131-142 (2024). https://doi.org/10.1016/j.jaci.2024.03.025.