Adaptations and alterations of maternal microbiota: From physiology to pathology

Pregnancy is a complex and continuously changing physiological process. With the increase in gestational age, a series of physiological changes, including hormone, metabolism, and immune, lead to the shift of microbiota of pregnant women. Growing studies have shown that the dysbiosis of microorganisms residing in multiple body sites is closely related to adverse pregnancy outcomes, especially preeclampsia, gestational diabetes mellitus, and preterm birth. In this review, we discussed the adaptations and alternations of the maternal microbiome in different sites (gut, vagina, and oral cavity) during normal and pathological pregnancies. Through the similarities and differences in microbial changes across different gestational diseases, we found three shared microbes (Bifidobacterium, Bacteroides, Dialister). In conclusion, we provide a comprehensive understanding of maternal microbial adaptions and changes, which brings insights into the association between maternal microbial dysbiosis and pregnancy complications and promotes the development of microbiota-specific approaches in the diagnosis and intervention of perinatal diseases. •Adaptations of the maternal intestine, vaginal, and oral microbiota under the physiological state of pregnancy.•Alternations of the maternal microbiota associated with preeclampsia, gestational diabetes, and preterm birth.•Bifidobacterium may serve important roles in gestational diseases.