New ideas about the maternal gut microbiome as a source of fetal programming

New genetic technologies that have emerged and been introduced into practice over the past 20 years, including 16s rRNA sequencing, have significantly expanded our understanding of the microbial composition of the human body. The gut is one of the most densely populated microbial niches in the human body. Numerous studies have shown the relationship of the gut microbiome with various non-communicable diseases, including diabetes mellitus, obesity, allergies and even mental disorders. The perinatal period, as one of the most hormonally dependent ones in human ontogenesis, has a direct impact on the composition of the intestinal microbiota, just as the microbiota itself can be a precursor and etiological cause of pregnancy complications. In this regard, the aim of this review article was to systematize data on the gut microbiota of the maternal body in normal and pathological pregnancy, as well as to analyze data on the interaction of the maternal gut microbiome with the fetal immune system. The review presents data on changes in the maternal intestinal microbiome in normal pregnancy, during infertility, as well as in pregnancy complicated with obesity, gestational diabetes mellitus and preeclampsia. The review also shows how the maternal microbiome is able to “educate” the fetal immune system in utero, thereby preparing the child, who develops in a sterile womb, for extrauterine life surrounded by a large number of various microorganisms. These mechanisms include the direct effect of not only the microorganisms themselves, but also, even largely, their metabolites — primarily short-chain fatty acids. All these presented data allow for concluding that the maternal microbiome is essentially a separate regulatory homeostatic system, along with the immune, endocrine and cardiovascular systems, which may determine the development of certain complications of pregnancy and shape the health of the unborn child. Interventions in the composition of the maternal gut microbiota may be a way to modulate the course of pregnancy and prevent major obstetric syndromes.