Role of cesarean section in the development of neonatal gut microbiota: A systematic review

BACKGROUND: The delivery mode is one of the factors affecting the type of colonization of the human gut. Gut colonization affects all stages of the human life cycle, and the type of gut microbiome can contribute to immune system function, the development of some diseases, and brain development; and it has a significant impact on a newborn’s growth and development. METHODS: Terms defined as MeSH keywords were searched by the databases, and web search engines such as PubMed, ClinicalTrials.gov, Embase, Scopus, ProQuest, Web of Science, and Google Scholar were searched between 2010 and 2020. The quality of each study was assessed according to the Newcastle–Ottawa scale, and seven eligible and high-quality studies were analyzed. FINDING: The abundances of Bacteroides and Bifidobacterium during the first 3 months of life; Lactobacillus and Bacteroides during the second 3 months of life; Bacteroides and Bifidobacterium during the second 6 months of life; and Bacteroides, Enterobacter, and Streptococcus after the first year of life were higher in vaginal delivery-born infants. While infants born by cesarean section (CS) had higher abundances of Clostridium and Lactobacillus during the first 3 months of life, Enterococcus and Clostridium during the second 3 months of life, and Lactobacillus and Staphylococcus after the first year of life. DISCUSSION: Delivery mode can affect the type of the human intestinal microbiota. The CS-born babies had lower colonization rates of Bifidobacterium and Bacteroides, but they had higher colonization rates of Clostridium, Lactobacillus, Enterobacter, Enterococcus, and Staphylococcus. Given the effect of microbiota colonization on neonatal health, it is therefore recommended to conduct further studies in order to investigate the effect of the colonization on the delivery mode and on baby’s growth and development. APPLICATION TO PRACTICE: The aim of this study was to investigate the role of CS in the development of the neonatal gut microbiota.