Objective: to analyze scientific evidence regarding the relationship between the type of birth and the microbiota acquired by newborns. Method: this integrative review addresses the role of the type of delivery on newborns’ microbial colonization. A search was conducted in the Medical Literature Analysis and Retrieval System Online/PubMed and Virtual Health Library databases using the descriptors provided by Medical Subject Headings (MeSH) and Health Science Descriptors (DeCS). Results: infants born vaginally presented a greater concentration of Bacteroides, Bifidobacteria, and Lactobacillus in the first days of life and more significant microbial variability in the following weeks. The microbiome of infants born via C-section is similar to the maternal skin and the hospital setting and less diverse, mainly composed of Staphylococcus, Streptococcus, and Clostridium. Conclusion: the maternal vaginal microbiota provides newborns with a greater variety of colonizing microorganisms responsible for boosting and preparing the immune system. Vaginal birth is the ideal birth route, and C-sections should only be performed when there are medical indications.