A systematic review and meta-analysis covering 5309 children demonstrated that both cesarean section and antibiotic use during the perinatal period lead to a reduction in bacterial diversity in newborns' intestines. Specifically, these procedures decrease the abundance of Bacteroidetes and Bifidobacteria.
However, according to data published in BMJ Paediatrics Open, exclusive breastfeeding is capable of partially restoring the disrupted microbial balance.
The early stage of life is critically important for the formation of the immune and microbial systems, which subsequently determines the risk of developing inflammatory, metabolic, and allergic diseases. Human gut colonization begins immediately after birth and actively develops during the first year of life, a process dependent on several factors: mode of delivery, maternal microbiota, use of antibiotics in the maternity ward, and type of feeding.
Traditionally, these factors have been considered in isolation, which hinders understanding their cumulative and combined influence on the newborn's flora.
The research team, led by Heidi Singleton from Bournemouth University, conducted a systematic review and meta-analysis that included 11 different studies. These studies compared vaginal births with cesarean sections and also assessed the impact of perinatal antibiotic use on gut microbiota composition within one year after birth. In all analyzed studies, children were born at term and did not have serious pathologies. The sample consisted of 5309 children from Asia, Africa, Europe, North America, and South America.
Despite methodological variations across different geographical areas, consistent trends were identified. Cesarean section was correlated with a decrease in the number of Bifidobacteria and Bacteroidetes, as well as an increase in the population of facultative anaerobes, including Clostridium, Enterococcus, and Staphylococcus. It should be noted that the overall analysis did not show a statistically significant difference in bacterial diversity between infants born vaginally and those born via cesarean section. Similarly, adding the effect of antibiotics to this relationship did not reveal substantial differences.
Nevertheless, in children who did not receive antibiotics, a trend towards increased microbial diversity was observed after the birth occurred vaginally. Statistical analysis confirmed patterns of reduced bacterial diversity and relative content of Bacteroidetes and Bifidobacteria in children born via cesarean section or who received antibiotics during the perinatal period. Vaginal births were associated with higher alpha diversity and earlier colonization of the gut by obligate anaerobes. Conversely, cesarean section slowed this process and increased the number of taxa associated with the environment and skin, such as staphylococci, corynebacteria, and enterobacteria.
Some of the studied works showed that antibiotic use in the first and third months of life leads to a decrease in Bifidobacteria levels. However, exclusive breastfeeding consistently promoted the restoration of the microbiota, increasing the number of Bifidobacteria and raising overall diversity. In one case, it was noted that children born via cesarean section who were exclusively breastfed had a gut microbiota profile indistinguishable from naturally born children by week 24.
The authors emphasize that due to the insufficient reliability of the data in this analysis, clinical recommendations regarding cesarean section or antibiotic therapy cannot be changed. They generally support current guidelines concerning the rational use of antibiotics and the benefits of breastfeeding.
