The present conception of neonatal microbiome formation

The neonatal period is critical in the development of the microbiome and the gastrointestinal tract. That is, the microbiome regulates not only the processes that are associated with the basic functions of the gastrointestinal tract, but is associated with the content of vitamins and micronutrients, affects the development of the nervous and endocrine systems of newborns. Fortunately, microbiome and immunity of pregnant get ready the infant for his inevitable complications. Although preterm birth has been connected with bacterial colonization of the amniotic cavity for many years, the dogma of a sterile intrauterine environment during a normal pregnancy has appeared only recently. Numerous placental microbiome and the occurrence of microorganisms in the amniotic cavity in normal pregnancy was demonstrated by metagenomic sequencing. The occurrence of microorganisms in intestine got from the operating room during resection of intestinal abnormalities immediately after birth and before feeding was also found in neonates born by caesarean section. In this literature review, we explore the update understanding of microbial colonization of the intestine and foundation of function of the gastrointestinal tract. We discuss how mother’s genital and extragenital pathologies, her diet, lifestyle, taking drugs during pregnancy form the microbiome of the fetus and its further development in the neonatal period. Also, equally important for the establishment of the neonatal microbiome are gestational age, mode of delivery, type of feeding and medication, including antibiotics. Therefore, in our opinion, the comparison of microbiota of a full-term newborn in vaginal birth and an infant born prematurely or by cesarean section is clinically significant for physicians in various fields. The study of changes in the microbial composition of the intestine is an important step in the diagnosis of pathological conditions in this period.