Gut and Reproductive Tract Microbiota Adaptation during Pregnancy: New Insights for Pregnancy-Related Complications and Therapy

Abstract

Pregnancy is characterized by maternal adaptations that are necessary to create a welcoming and hospitable environment for the fetus. Studies have highlighted how the microbiota modulates several networks in humans through complex molecular interactions and how dysbiosis (defined as quantitative and qualitative alterations of the microbiota communities) is related to human pathologies including gynecological diseases. This review analyzed how maternal uterine, vaginal, and gut microbiomes could impact on fetus health during the gestational period. We evaluated the role of a dysbiotic microbiota in preterm birth, chorioamnionitis, gestational diabetes mellitus and pre-eclampsia. For many years it has been hypothesized that newborns were sterile organisms but in the past few years this paradigm has been questioned through the demonstration of the presence of microbes in the placenta and meconium. In the future, we should go deeper into the concept of in utero colonization to better understand the role of microbiota through the phases of pregnancy. Numerous studies in the literature have already showed interesting results regarding the role of microbiota in pregnancy. This evidence gives us the hope that microbiota modulation could be a novel strategy to reduce the morbidity and mortality related to pregnancy complications in the future.

Association Between Vaginal Gardnerella and Tubal Pregnancy in Women With Symptomatic Early Pregnancies in China: A Nested Case-Control Study

“…Several studies have shown that vaginal microbiota became less diverse, more stable, and were dominated by Lactobacillus in women with normal pregnancies ( DiGiulio et al., 2015 ). Consistent with the results of our studies, some findings have also indicated that pregnancy complications were associated with the increased relative abundance of anaerobes, including Gardnerella , Prevotella , and Atopobium ( Fettweis et al., 2019 ; Siena et al., 2021 ). Moreover, the most frequently described harmful change affecting the vaginal microbiome in women of reproductive age, bacterial vaginosis (BV), is characterized by a decrease in relative Lactobacillus abundance and an increase in anaerobic bacteria, primarily Gardnerella vaginalis ( Fredricks et al., 2005 ).…”

Contribution of vaginal infection to preterm premature rupture of membrane and adverse pregnancy outcome

“…Vaginal microbial changes are associated with an increase in local activation of the innate immune system and induction of the inflammatory cascade, which may induce membrane disruption with preterm labor or PPROM [20]. In current study normal flora was significantly prevalent in pregnant female with normal pregnancy.…”

Microbiome Characteristics in Early Threatened Miscarriage Study (MCETMS): a study protocol for a prospective cohort investigation in China

“…The gut microbiota participates in the construction of the intestinal mucosal immune barrier and metabolic activities, thus playing a crucial role in shaping and regulating the immune system and immune response 6. As previously reported, Proteobacteria and Actinobacteria as proinflammatory microbiota function to protect the mother and fetus from infections 7. Liu et al 8 previously showed that the intestinal microbiota regulates related proinflammatory cytokines through its metabolites to have a biological impact on abortion.…”

“… 6 As previously reported, Proteobacteria and Actinobacteria as proinflammatory microbiota function to protect the mother and fetus from infections. 7 Liu et al 8 previously showed that the intestinal microbiota regulates related proinflammatory cytokines through its metabolites to have a biological impact on abortion.…”