Nursing vs pumping: Breastfeeding practices may affect the transfer of maternal bacteria to the infant gut
The infant gut microbiome is characterized as low in diversity that’s dominated primarily by bifidobacteria and unique to the individual. During approximately the first three years of life, the gut microbiome develops and is largely shaped by various factors including delivery mode (vaginal vs Cesarean birth), maternal antibiotic use, home environment and breastfeeding vs formula feeding. The gut microbiome is later influenced by diet and how long the child was breastfed which affects the gut microbiota composition later in early childhood.
Several recent studies have shed light on the benefits breastmilk have on infant health and their developing gut microbiomes because it contains various components, such as beneficial bacteria, prebiotics called human milk oligosaccharides as well as immune cells, that confer long-term benefits for babies’ health including preventing malnutrition. Additionally, breastfed babies have been found to have less instances of allergies and metabolic disease, yet it is unknown how breastfeeding practices (i.e. nursing vs. pumping) affects the breastmilk composition and infant gut microbiome.
Pumping breastmilk has become a popular and convenient way for mothers to continue to feed their babies breastmilk, yet it is unknown as to whether this method affects the transfer of other non-milk-derived bacteria from the pump or bottles compared to maternal skin for example.
Meghan Azad’s research group from Canada analyzed fecal and breastmilk samples from 1,249 mother-infant pairs as part of the CHILD Cohort Study to examine how breastfeeding practices, duration and exclusivity affect the infant gut microbiota composition over a one year period. Interestingly, they discovered that exclusive nursing vs pumping influenced the infant gut microbiota composition.
The researchers observed clear differences in the infant gut microbiome of babies who were exclusively breastfed at 3 months versus those who were no longer fed breastmilk.
As expected, the bacterial composition of breastmilk and the infant gut microbiome differed greatly, but at 3 months the infant gut and milk microbiota of infant-mother pairs were more similar compared to random pairings, which is in line with a previous study. They also observed that no bacteria was commonly shared among the mother-infant pairs suggesting that breastmilk composition is highly unique to the mother and transfer of breastmilk bacteria to infant is dependent on various factors including duration and exclusivity of nursing.
This study provides evidence that specific bacteria from mother’s milk can be directly transferred to the infant gut microbiota, which influences the infant gut microbiota composition and therefore could affect the child’s long-term health such as childhood asthma and obesity.
Breastfeeding practices appear to affect the composition and transfer of bacteria to the infant gut and may affect the child’s long-term health. For example, pumping was associated with a depletion of some of the shared bacteria between breastmilk and the infant gut and provided a slightly weaker protection against childhood asthma and obesity compared to exclusive breastfeeding. Moreover, habitual pumping was shown to change breastmilk composition possibly through the heating, freezing or thawing or breastmilk or other due to other causes.
More studies in different populations are needed to further understand the potential therapeutic implications of shared bacteria that co-occur in breastmilk and the infant gut. Despite these findings, I don’t think that pumping should be discouraged as it still provides baby with nutritious breastmilk and beneficial bacteria.
Reference: Fehr et al. Breastmilk feeding practices are associated with the co-occurrence of bacteria in mother’s milk and the infant gut: the CHILD Cohort Study. Cell Host & Microbe; 2020: 28: 1-13. https://doi.org/10.1016/j.chom.2020.06.009
