Body site-specific micro-and lactobiota in genitourinary infections during pregnancy

Siiri KõljalgEpp SeppJelena Štšepetova (Shchepetova)Eva-Liina SüüdenTiia ReimandMadis JaaguraAndres SalumetsReet Mändar^*

• University of Tartu, Tartu, Estonia

Background Immunological, metabolic and hormonal changes occur during pregnancy, which can affect the composition and function of the microbiota. These changes can influence pregnancy outcomes and the health of mother and baby. We aimed to characterize the microbiota of pregnant women across various body sites and examine the clinical and population-specific factors associated with its composition. Material and methods 105 pregnant women with gestational age between 15-20 weeks were recruited in the Women’s Clinic of Tartu University Hospital, Estonia. Microbiota samples of cervix (C, n=84), vagina (V, n=85), urine (U, n=105), mouth (M, n=85) and rectum (R, n=84) were analysed using Illumina NextSeq2000. Results Firmicutes was the most common phylum in all investigated locations. Lactobacillus was the most abundant genus in C, V and U samples (mean proportions 76%, 77% and 59%, respectively) while its mean relative abundance was significantly lower in oral (2.8%) and rectal (6.2%) samples. L. iners was the most frequent Lactobacillus species in genitourinary samples followed by L. unid/crispatus, L. jensenii and L. gasseri. The mean relative abundance of L. iners and L. unid/crispatus in these locations was relatively equal (36 vs. 32% in C, 35 vs. 33% in V, 25 vs. 27% in U). Higher diversity of total urogenital microbiota was associated with chorioamnionitis and metroendometritis at delivery, and genitourinary infections during the second half of pregnancy. The latter was associated with lower Lactobacillus species diversity in C, V and U samples. These women had also lower proportion of L. unid/crispatus (in C and V samples) and L. gasseri (in C, V and U samples), while higher proportion of L. iners in C samples and higher proportion of other bacteria in C and U samples. Conclusions Microbiota of pregnant women is linked to health profile and lifestyle factors and varies in different body regions but is remarkably similar in cervix and vagina. Higher abundance of Lactobacillus species in mid-pregnancy, particularly L. crispatus and L. gasseri, potentially provides protection against later genitourinary tract infections during pregnancy. This research provides a foundation for future studies aimed at developing more effective strategies to support healthy pregnancy.