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Breastfeeding restores perturbations in the infant’s gut microbiota caused by the mode of delivery

Aug 11, 2023 | Other Medical Disciplines

In this longitudinal cohort study, the Chinese researchers investigated the impact of delivery mode and feeding pattern on the dynamics of the infant’s gut microbiota from six weeks to six months after delivery. They also examined the correlation between the infant’s susceptibility to respiratory infections and changes in the gut microbiota caused by the mode of delivery and feeding pattern. The results showed that breastfeeding restored perturbation in the infant’s gut microbiota caused by the mode of delivery (Cesarean section), and reduced susceptibility to respiratory infections in the first months of the infant’s life.

Numerous perinatal factors influence the maturation of gut microbiota, including delivery mode, feeding pattern, antibiotic exposure, and gestational age. The authors pointed out the importance of recent studies which have demonstrated that delivery mode is a major determinant of the gut microbiota during the first weeks of life. Cesarean section delivery disrupts the natural transmission of the gut microbiota from mothers to offspring. As a result, the lack of specific bacterial taxa in infants delivered by Cesarean section disturbs the maturation of the infant intestine and immune systems. The decrease in the health-promoting Bifidobacterium and the rise in potentially pathogenic Enterococcus, Staphylococcus, Streptococcus, and Klebsiella in infants delivered by Cesarean section have been associated with higher incidence of respiratory infections during the first year of life. This suggests that alterations in the gut microbiota, induced by Cesarean delivery, may have a role in disease susceptibility. By contrast, the enrichment of Bifidobacterium, Escherichia, Bacteroides, and Parabacteroides in vaginally delivered infants can promote the utilization of human milk oligosaccharides and immune stimulation in early life. However, the effect of the delivery mode gradually decreases by six months of life or earlier, indicating that the gut microbiota could recover after the Cesarean section delivery. It is important to note a difference between the gut microbiota in exclusively breastfed and formula-fed infants, even when specific components are added to the formula to promote breastfed-like microbial communities. 

About the study

The study included 139 infants at six weeks postpartum. 73% (101/139) of them completed the six-month follow-up. Stool samples were collected from each infant at six weeks (n= 139) and six months postpartum (n= 101). The prenatal and perinatal data about the infants, including maternal age, gravidity, pre-pregnancy body mass index, delivery mode, gestational age, infant sex, birth weight, feeding pattern, and the occurrence of respiratory infections during the first six months of age, were obtained from electronic medical records and questionnaire surveys.

The feeding pattern was divided into two types: exclusive breastfeeding, defined as feeding with breast milk exclusively after birth, and mixed feeding, defined as feeding with a mixture of breast milk and formula milk in varying proportions. Respiratory infection events are defined as the occurrence of the symptoms reported by mothers, such as pneumonia, bronchitis, and fever (higher than 38 °C), accompanied by snuffling, sneezing, coughing, or wheezing.

Results

Out of 139 infants, 93 infants (67%) were born by vaginal delivery, and 46 by Cesarean section delivery. The clinical variables were similar between the vaginally delivered and Cesarean section-delivered groups, except for gestational age, which was related to the delivery mode.

The researchers first compared gut microbiota composition and community structure found at six weeks and six months of age. These results demonstrated a more homogeneous microbial community cluster at six months postpartum. Clostridium sensu stricto1, Klebsiella, and Streptococcus were more abundant at six weeks, whereas Bifidobacterium, Bacteroides, Escherichia-Shigella, and Veillonella were enriched at six months of age.

The authors then analyzed how delivery mode affected the infant’s gut microbiota, and found a difference in the composition and structure of the gut microbiota between infants delivered by Cesarean section and vaginally delivered infants at six weeks postpartum. These findings confirmed that the mode of delivery is a major determinant of the gut microbiota during early life. The observed difference disappeared at six months of age, indicating that changes in the gut microbiota related to the delivery mode diminish gradually throughout infancy.

The researchers also hypothesized that the feeding pattern influences the impact of delivery mode on the infant’s gut microbiota. To examine this presumption, they divided 101 infants at 6 months postpartum into two groups based on their feeding patterns: breastfeeding and mixed feeding groups. In the mixed feeding group, the stool samples analysis showed a significant difference in the gut microbiota structure between vaginally delivered infants and infants delivered by Cesarean section. However, in the breastfeeding group, there was no significant difference in the gut microbiota structure between vaginally delivered and Cesarean section-delivered infants. These results suggest that breastfeeding alleviated a disturbance in the gut microbiota observed in infants delivered by Cesarean section.

In the subsequent cross-sectional analysis, researchers compared the relative abundance of the top ten genera between vaginally delivered and Cesarean section-delivered infants. At six weeks postpartum, all vaginally delivered infants were enriched in Bacteroides and Escherichia-Shigella. However, infants delivered by Cesarean section were depleted of these commensal genera and enriched in Klebsiella, Veillonella, and Enterococcus.

At six months postpartum, breastfeeding restored the observed microbial shift in the infant’s gut microbiota, induced by a delivery mode. Gut microbial profiles in vaginally delivered infants and infants delivered by Cesarean section in the breastfeeding group were similar. In the mixed-feeding group, there was still a difference in relative abundances of specific taxa between infants who were vaginally delivered and those who were delivered by the Cesarean section. Infants delivered by Cesarean section had a lower relative abundance of Bacteroides and a higher abundance of Klebsiella, Veillonella, and Streptococcus. The relative abundances of Escherichia-Shigella were comparable in both groups.

The correlation analysis revealed that changes in the infant’s gut microbiota induced by delivery mode correlated with the incidence of respiratory infections. During the first 6 months of the infant’s life, the incidence of respiratory infections was significantly higher in infants delivered by Cesarean section (9/71) than in vaginally delivered infants (10/30). Genera associated with Cesarean section delivery (low Escherichia-Shigella and high Klebsiella) were enriched in infants who suffered from respiratory infections. In conclusion, this study demonstrated the indispensable nutritional and immune benefits of breastfeeding. 

This article was published in Frontiers in Microbiology.

Journal Reference

Liu Y, et al. A health-promoting role of exclusive breastfeeding on infants through restoring delivery mode-induced gut microbiota perturbations. Front. Microbiol. 2023; 14:1163269. (Open Access)   https://www.frontiersin.org/articles/10.3389/fmicb.2023.1163269

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