Microbial colonization of the infant occurs during a critical time window for immune and gastrointestinal development. Infant colonization sets the stage for the adult microbiome. The nature of infant environmental exposures, acting through the microbiome, affect the likelihood of developing childhood and adult diseases such as obesity, food allergy, and inflammatory bowel disease. Many bacterial sources for the infant derive from the maternal microbiota. Therefore, beneficial infant colonization is dependent upon maternal genetics, environmental exposures and diet before and during pregnancy as well as during breast feeding.
The mother not only gives the newborn everything for life but she also gives the newborn some of her microbiota through delivery, prebiotics, and breast milk.
Delivery
The current fetus microbial model leads us to believe there are no bacteria present in the fetus (though they are surrounded by microbiota in the womb) and it’s not until childbirth that the first microbes are transferred to the baby through the birth canal during delivery. So according to what we know as of today, if that baby doesn’t come out of that birth canal, the baby does not get inoculated with healthy probiotic bacteria.
As of last month, a study dropped, proving that if a Cesarean-delivered newborn was swabbed with the mothers vaginal fluid, their gut, oral and skin bacterial communities were enriched with vaginal biome! So for all you parents out there who have the best intentions of delivering vaginally, but your life or the life of your unborn baby, or both, are at risk, there is a simple solution that is now officially backed by the science method (1).
Natural Prebiotics
The vernix caseosa, the waxy skin coating of a fetus, is shed into the amniotic fluid as the fetus approaches term. While still in utero, the near-term fetus swallows amniotic fluid containing pieces of vernix. While not digestible by human enzymes the vernix caseosa provides a good medium for bacteria to grow on. Once the infant begins to breastfeed, breast milk contains additional prebiotics. Colostrum contains especially high concentrations of human milk oligosaccharides (HMOs), which are indigestible by human enzymes alone. Their synthesis requires up to ten percent of the total energy expended to produce human milk. These oligosaccharides, like the vernix, promote growth of intestinal microbes (2).
Breast Milk
Breast milk contains both innate and adaptive immune components that inhibit pathogens from colonizing the infant gut. As part of the innate immune system, breast milk contains antibacterial peptides, such as lactoferrin and lysozyme. These antibacterial peptides provide broad spectrum bacteriostatic and bacteriocidal checks on microbial growth. Breast milk contains glycans that mimic cell surface adhesion molecules on the infant’s intestinal epithelium. These glycans act as decoy receptors to specific intestinal pathogens, providing a further level of protection for the infant.
Breast milk has long been known to contain bacterial DNA. Modern culture-independent techniques identified gut-associated obligate anaerobes in addition to facultative anaerobes in the breast milk as a source of diversity in the infant gut (3). Through these prebiotic and probiotic mechanisms, breast milk shapes the intestinal microbiome. Exclusively breast-fed infants have overall greater diversity of the microbiome when compared to exclusively formula-fed infants
- Bromberger, P., Lawrence, J. M., Braun, D., Saunders, B., Contreras, R., & Petitti, D. B. (2000). The influence of intrapartum antibiotics on the clinical spectrum of early-onset group B streptococcal infection in term infants. Pediatrics, 106(2), 244-250.
- Newburg DS, Walker WA. Protection of the neonate by the innate immune system of developing gut and of human milk. Pediatr Res. 2007;61(1):2–8.
- Jost T, Lacroix C, Braegger C. Assessment of bacterial diversity in breast milk using culture-dependent and culture-independent approaches. Brit J Nutr. 2013;110:1253–1262.
