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01/26/2026

Scientists Discover Breast Milk Carries Key Gut Bacteria to Infants
By University of Chicago Medical Center
January 21, 2026
Human breast milk contains its own microbial ecosystem, and new research suggests these microbes may help seed an infant’s gut.

Most discussions of breast milk highlight nutrients, antibodies, and the parent infant bond, while the microbes in milk get far less attention. Yet human milk also contains its own small microbial community, and these bacteria may help steer how a baby’s gut microbiome develops, with downstream effects on nutrient absorption, metabolism, and immune maturation.

A new study published in Nature Communications offers one of the clearest views so far of how different bacterial lineups in human milk may contribute to building infants’ gut microbiomes.

Mapping the milk microbiome

Studying the breast milk microbiome is challenging because milk is fatty and typically contains relatively few bacteria, making it hard to extract enough genetic material for detailed analysis.

“Breast milk is the recommended sole source of nutrition for an infant’s first months of life, but important questions about the milk microbiome remained unanswered because the analytical challenges are intimidating,” said first author Pamela Ferretti, PhD, a postdoctoral researcher in the Blekhman Lab at the University of Chicago. “We decided to tackle this endeavor because our collaboration presented a unique opportunity to combine key resources.”

Those resources included hundreds of milk samples collected as part of the Mothers and Infants LinKed for Healthy Growth (MILk) study, led by Ellen Demerath, PhD, at the University of Minnesota and by David Fields, PhD, at the Oklahoma University Health Sciences Center. At UChicago, Ferretti and her colleagues paired those samples with metagenomic methods and extensive experience working with microbiome datasets, including Ferretti’s specialized background in infant microbiomes and transmission analysis. In earlier work, she examined how microbes from different maternal body sites — such as mouth, skin, and vaginal cavity — contribute to the microbiomes that babies develop.

After analyzing 507 breast milk and infant stool samples from 195 mother–infant pairs, the researchers found that milk contained a characteristic mix of bacteria dominated by bifidobacteria, including Bifidobacterium longum, B. breve, and B. bifidum. More than half of the milk samples contained B. longum, and that same species was abundant in over 98% of the infants’ gut microbiomes.

“Even though B. longum is well-documented as being highly prevalent in the infant gut, it was surprising to find such a strong signature of that species in the breast milk samples because previous milk studies mostly reported other bacterial taxa like Staphylococcus and Streptococcus,” Ferretti said. “We think these results will prompt some reevaluation in the field.”

Tracing microbes from milk to the infant gut
Most prior studies analyzing bacterial DNA in breast milk used a relatively inexpensive, fast technique called amplicon sequencing, which targets a limited number of predetermined genomic regions for each experiment. This method is good for efficiently identifying species within a mixed sample, but it leaves most of the bacterial genome unexamined.

“Metagenomic analysis is trickier and more complicated, but it really paid off because it allowed us to obtain information at the level of different bacterial strains — which is key, because that’s the only level where we could actually claim to know about transmission,” Ferretti said.

The paper reported 12 instances in which the same exact strain was found in a mother’s breast milk and in the gut of her infant, which is a very strong indication that the transmission happens vertically via breastfeeding.

Some of these shared strains were beneficial commensal species such as B. longum and B. bifidum, which help digest human milk sugars and support healthy gut development. Others, however, were pathobionts — microbes like E. coli and Klebsiella pneumoniae that can live harmlessly in healthy individuals but have the potential to cause infection under certain conditions. The authors note that all mothers and infants in the study were healthy, indicating that these species’ presence in milk does not inherently signal disease but rather reflects the microbial diversity that can be transferred during breastfeeding.

Interestingly, the team also saw specific strains of bacteria usually associated with the mouth — such as Streptococcus salivarius and Veillonella species — in milk samples. They realized this as potential evidence of “retrograde flow” during breastfeeding: as the baby feeds, tiny amounts of oral bacteria may travel back into the ni**le and ducts and become part of the milk microbiome.

Expanding human milk research
Ferretti noted that the study not only sheds light on microbial transmission but also fills a major gap in available data for scientists studying early-life health.

“This study nearly doubled the number of metagenomic breast milk samples that are publicly available, and pairs them with extensive information on mothers’ health and lifestyle,” Ferretti said. “We’re hopeful that our findings and future analyses that use this dataset will really push the field forward.”

In subsequent studies, the researchers hope to take their analysis to the next level with a multi-omic approach, including analyzing metabolites like human milk oligosaccharides (HMOs) and examining the “exposome” of environmental factors like PFAS and antimicrobial resistance that can be passed along through milk.

“Ultimately, we’re interested in looking at longer health trajectories to see if factors in breast milk and early life are predictive of health outcomes later in life,” Ferretti said.

Reference: “Assembly of the infant gut microbiome and resistome are linked to bacterial strains in mother’s milk” by Pamela Ferretti, Mattea Allert, Kelsey E. Johnson, Marco Rossi, Timothy Heisel, Sara Gonia, Dan Knights, David A. Fields, Frank W. Albert, Ellen W. Demerath, Cheryl A. Gale and Ran Blekhman, 22 November 2025, Nature Communications.
DOI: 10.1038/s41467-025-66497-y

https://scitechdaily.com/scientists-discover-breast-milk-carries-key-gut-bacteria-to-infants/

01/13/2026

So interesting - thx for the share Carol !

Animals that researchers call “supersucklers” come back for their mother’s milk even after they can hunt, mate and fend for themselves.

01/08/2026

Somewhere between the quiet breaths, the tiny fingers resting on your skin, and the slow rhythm of your baby feeding, the world softens. Breastfeeding is not just nourishment, it is comfort, safety, and love all wrapped into one sacred moment. It is a place where worries pause, hearts sync, and a baby learns that this is where they belong. In these simple, tender moments, you are giving your baby everything they need most.

01/08/2026

Breastfeeding and RSV: Studies confirm what many already suspect—breastfeeding plays a powerful role in protecting infants. Research shows that babies who aren't breastfed are more likely to be hospitalized, need oxygen, or end up in the ICU with RSV. While breastfeeding doesn’t prevent RSV entirely, it does make a big difference in how severe the illness is.

Want to know more about the latest findings and prevention strategies? Click to read the full article from our Breastfeeding and Lactation Resource Department.

"Respiratory Syncytial Virus (RSV) in Infants There has been much media coverage about respiratory syncytial virus (RSV) becoming a major problem in infants this fall. The LLL Alliance Professional Liaison Department recently did a search for current literature regarding breastfeeding and RSV. All the studies in the search found that breastfeeding is protective. The lack of breastfeeding in infants caused a higher rate of RSV. Lack of breastfeeding also resulted in more severe cases, many requiring oxygen therapy and a higher rate of admission to the pediatric ICU. One of these studies was from 2019, in the journal Clinical and Experimental Pediatrics titled “Positive association of breastfeeding on respiratory syncytial virus infection in hospitalized infants: a multicenter retrospective study.” This article states that the infants who were hospitalized were more likely to have been breastfed for two months or less or not breastfed at all. It also mentions that having RSV is “nearly universal” in children by their second birthday. (Generally, the older a healthy baby is when they get RSV, the milder it is. Often parents think it’s just a cold.) The other two articles are both from 2022. The first is from The Journal of Pediatrics, “Impact of Breastfeeding on the Incidence and Severity of RSV Bronchiolitis in Infants: Systemic Review,” which mentions exclusive breastfeeding for greater than four months significantly lowering hospitalization and needing to use oxygen. It says that it appears that human milk may protect against serious airway damage. The second article is from Early Human Development, “New strategies prevention of respiratory syncytial virus (RSV),” a brand new article from the November 2022 issue. It mentions hygiene, breastfeeding and passive immunization using Palivizumab (a monoclonal antibody therapy currently being used for high risk babies) as being the current prevention strategies. They also state that in the near future, monoclonal antibodies and maternal vaccination during pregnancy will play an important role. There was no study found that indicates that breastfed infants are less likely to be infected, just that their cases are usually less severe. However, prematurity, lung disease, and heart disease can complicate cases. Limiting exposure, hand washing, and continuing to breastfeed seem to be most effective to prevent illness. "

https://lllalliance.org/wp-content/uploads/2025/01/Respiratory-Syncytial-Virus-RSV-in-Infants-LLL-Alliance-10.2022-1.pdf?

10/2022
Credit LLL Alliance For Breastfeeding Education

https://www.facebook.com/photo/?fbid=1305035325004014

01/02/2026

😃

01/02/2026

and they don’t judge!

Mother’s singing has profound effects on a baby’s brain, acting almost like a natural medicine. Studies show that hearing her voice can calm a baby’s heart rate and regulate their nervous system in mere seconds, even if she thinks she cannot sing.

The soothing qualities of a mother’s voice provide safety and predictability. Babies are highly attuned to vocal tone, rhythm, and melody, which help them feel secure and supported. This effect strengthens emotional regulation and attachment.

Singing during daily routines feeding, changing, or bedtime offers consistent opportunities to promote calm and connection. The brain registers these moments as positive, helping infants manage stress and develop resilience.

Even imperfect singing works. Babies respond to the emotional intent and presence behind the voice, not technical skill. The act of singing itself fosters neural development, reinforcing pathways related to language, attention, and social bonding.

Parents can use singing as a simple, accessible tool to soothe, engage, and support their baby’s nervous system. Incorporating short songs or lullabies throughout the day enhances both emotional and cognitive development while strengthening the parent-child bond.

12/16/2025

A subject always worth revisiting

Has somebody told you that your baby doesn’t need to breastfeed at night past a certain age? This age often varies by advisor. However, science tells us that in many cases, this simply isn’t true. Why? Babies and mothers are different and these differences affect baby’s need for night feedings...

12/14/2025

Thank you to Representative Eric Swalwell and Senator Tammy Duckworth for co-sponsoring the BABES Enhancement Act. This new law brings greater accountability to how TSA handles breast milk and breastfeeding equipment

A New Law Will Finally Give Real Protection To Parents Traveling With Breast Milk
By Kim Elsesser, Senior Contributor.
Dec 03, 2025,

"Summary
Despite a 2016 law, parents traveling with breast milk often faced frustrating, unhygienic TSA screenings. Emily Calandrelli's advocacy, sparked by her own negative experience, led to the new BABES Enhancement Act. This law mandates clear guidelines, consistent training, and oversight, ensuring safe, hygienic travel for breastfeeding parents and empowering working mothers.

For countless parents traveling with breast milk, airport security has too often meant navigating a frustrating and humiliating process, despite a 2016 law meant to protect them. The 2016 Bottles and Breastfeeding Equipment Screening (BABES) Act was supposed to ensure breast milk, formula and the tools needed to transport them could pass through TSA checkpoints without incident. Yet, despite the law, many parents still faced inconsistent treatment, from being forced to dump milk to facing unhygienic inspections.

One mother’s negative experience at TSA inspired her to push for change. After TSA agents forced her to leave her cold packs behind, Emily Calandrelli, the host of Netflix’s Emily’s Wonder Lab and YouTube’s Emily’s Science Lab, began working with lawmakers to strengthen the protections that weren’t being enforced. Her efforts have now resulted in a new law that closes the gaps left by the original legislation. Passed last month, the BABES Enhancement Act is designed to ensure parents can travel with breast milk and the equipment needed to safely store and transport it, without confusion or unhygienic treatment.

The incident that inspired Calandrelli’s activism occurred in 2022. Calandrelli was taking her first work trip away from her 10-week-old son and planned to pump before a five-hour flight. She needed to store the milk for her baby and brought a gel pack to keep it cold, but the pack thawed on the way to the airport. TSA agents said she couldn’t bring it on board because it wasn’t fully frozen. When she asked for a supervisor, he questioned why her baby wasn’t with her and told her it wouldn’t have been a problem if she had had the child with her. She was told she had to throw out the ice packs or check them.

“Yesterday, I was humiliated that I had to explain to three grown men that my breasts still produce milk when I’m not with my child. Yesterday, I was embarrassed telling them about my fear of mastitis if I didn’t pump. Today, I’m furious,” Calandrelli described in a tweet at the time.
After sharing her story publicly, Calandrelli was inundated with messages from women who’d faced similar treatment. Many described that their breast milk was handled without basic hygiene, and others told her they faced pushback when they asked the TSA inspectors to put on clean gloves. Some described to her how TSA officers dipped test strips directly into their breast milk, while one mother was told she needed to sip her own milk to prove it wasn’t dangerous. Still others recounted being forced to dump milk that exceeded the standard three-ounce liquid limit, despite breast milk being explicitly exempt from that rule.

Instead of simply venting about her own experience and moving on, Calandrelli channeled her frustration to help other pumping mothers.

BABES Enhancement Act Passed
As a result of her efforts, the BABES Enhancement Act was signed on November 25 and will force TSA to be accountable for how it treats breast milk, formula and related equipment. First, TSA must develop clear hygienic screening guidelines under the guidance of nationally recognized maternal health organizations. The law also calls for consistent officer training and requires TSA to better communicate parents’ rights at security checkpoints. To ensure real accountability, an independent watchdog will audit TSA’s compliance and help prevent future mishandling.“This is a huge win for traveling mothers. The BABES Act ensures TSA officers receive proper training and follow hygienic standards so parents can travel with confidence. This is about giving families peace of mind and making sure babies have the nutrition they need,” Representative Eric Swalwell, the lead House sponsor, said in a statement.

Calandrelli says the bill’s unanimous passage in both the House and Senate gave her a sense of optimism. In a moment when bipartisan agreement is rare, she found it meaningful that lawmakers from both parties championed the effort. Although the primary sponsors in the House and Senate were Democrats, she explains, “The Republican leaders and co-sponsors were incredibly helpful, and I want to make sure they get their credit as well.”

Making It Easier for Mothers to Keep Pumping
As a result of her own issues traveling with breast milk, Calandrelli told me she stopped breastfeeding earlier than she planned. She even tried a service that ships milk for traveling parents, but she says, “They lost my milk in transit, and I lost a lot of milk.” The uncertainty about whether her breast milk would reach her destination made it too complicated. “I stopped breastfeeding because it was just too hard with work,” she explained. She noted that the American Academy of Pediatrics recommends breastfeeding for up to two years, yet the U.S. provides few structural supports for mothers. “It all just felt like this one big irony, and, for me, what that resulted in, was me stopping breastfeeding early so that I could continue working,” she said.

With the passage of this bill, parents can finally hope to travel knowing their breast milk will make it through the checkpoint and be treated hygienically. As a result, it could empower more working moms to continue breastfeeding longer, should they choose to.

Still, Calandrelli urges families to familiarize themselves with the TSA rules and keep them handy while traveling so they can advocate for their rights in the moment. “I didn’t know how to advocate for myself, and I think that if I had known the policy, and I knew to use the word like ‘this is a medically necessary item,’ then maybe my problem would have been solved on the spot,” she explained."

https://www.forbes.com/sites/kimelsesser/2025/12/03/a-new-law-will-finally-give-real-protection-to-parents-traveling-with-breast-milk/

12/12/2025

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