Transfer of Microbiome from Mother to Child: A Key but Fragile Process

Industrialization and Its (Unrecognized) Consequences

The development that many civilized countries have undergone in recent decades brings significant changes in lifestyle and medical advancements. However, the impact of these changes on gut microbiota has not been given enough attention, despite the potential link to several diseases associated with industrialization, such as inflammatory bowel disease, obesity, and atopy. The microbiota plays an essential role in early postnatal physical, cognitive, and immunological development (its role in prenatal development is still under discussion) and can influence a person's health for the rest of their life.

Where the Microbiome Comes From

It is known that a healthy gut microbiome is formed in the first months of life. Its origin is not precisely understood, but maternal microbiota is at least one of the sources, as identical bacterial strains have been found in the microbiomes of mothers and their offspring. Successful microbial transfer between mother and child depends on several conditions, which can be divided into three main categories or levels of transfer:

• the presence of desirable microbiota in the mother's body
• sufficient contact between mother and child
• the child's ability to accept the microbes

All these conditions can be disrupted by various factors.

The Nature of Maternal Microbiota

The mother’s microbiota is shaped and modified by her genetic makeup, dietary habits, health status, and medication use. Studies have shown the positive effect of sufficient fiber intake and potentially negative effects of artificial sweeteners and food additives on gut microbiota. Maternal health issues such as mastitis, gestational diabetes, group B streptococcal infections, and bacterial vaginosis are linked to microbiota alterations.

Microbiota composition can also be influenced by medication use, particularly antibiotics, but also cancer chemotherapy before pregnancy. Antibiotic use can play a role during pregnancy, childbirth, and breastfeeding—whether by transferring the drug through breast milk into the infant’s digestive tract or by modifying the microbial composition of breast milk.

Contact Factors and the Child Itself

Authors identified the type of delivery (vaginal delivery leads to massive exposure of the newborn to maternal microbial colonization, while this step is literally “bypassed” in cesarean section) and breastfeeding (compared to formula feeding, breast milk significantly better supports and enhances the microbial colonization of the infant's digestive tract, although the origin of the microbiota in breast milk remains a subject of debate and hypotheses) as crucial steps in microbial transmission between mother and child. The potential role is also attributed to interventions such as enema administration or epidural anesthesia during childbirth.

The last step, the colonization of microbes in the infant's digestive tract, can be influenced by the newborn’s maturity, genetic makeup, health complications (asthma, food allergies, infant colic, etc.), “competition” between bacterial strains, and antibiotic treatment—particularly antibiotic administration before 6 months of age or a higher number of antibiotic treatment cycles per year are negative factors.

Conclusion

Although all determinants of healthy microbial colonization of the newborn are not yet fully understood, current knowledge allows us to avoid many unnecessary microbiota alterations. Key factors include awareness of potential disruptive factors and understanding the significance of healthy microbiota in the first months of life. Both gynecologists and pediatricians, as well as parents themselves, should be informed.

(luko)

Source: Van Daele E., Knol J., Belzer C. Microbial transmission from mother to child: improving infant intestinal microbiota development by identifying the obstacles. Crit Rev Microbiol 2019 Sep-Nov; 45 (5-6): 613-648, doi: 10.1080/1040841X.2019.1680601.