The influence of dysbiotic disorders and local inflammatory reactions in the reproductive tract on the development of preterm birth

Objective: To investigate how the state of microbiocenosis and the expression profile of immune response genes in the reproductive tract of pregnant women affect the occurrence of preterm birth.

Materials and methods: This study included 228 women who were divided into groups based on gestational age at delivery. Fifty-two patients gave birth at a gestational age of 22.0–27.6 weeks, 56 at a gestational age of 28.0–31.6 weeks, 60 at a gestational age of 32.0–33.6 weeks, and 60 at a gestational age of 34.0–37.0 weeks. Each group was divided into subgroups categorized according to whether they had preterm prelabor rupture of the membranes (PPROM) or spontaneous onset of labor (SPB) without PPROM. Subgroups included women who delivered at 22.0–27.6 weeks (PPROM n=28, SPB n=24), 28.0–31.6 weeks (PPROM n=30, SPB n=26), 32.0–33.6 weeks (PPROM n=35, SPB n=25), and 34.0–37.0 weeks (PPROM n=32, SPB n=28). A total of 125 patients with PPROM and 103 with SPB without PPROM were enrolled. The control groups consisted of pregnant women with threatened preterm birth who delivered at term (n=80) and those with a normal pregnancy who delivered at 37.0–41.0 weeks (n=72). All patients were tested for vaginal microbiocenosis using the Femoflor method with determination of local inflammatory response by measuring mRNA expression levels of cytokine genes in vaginal scrapings.

Results: There were significant differences between the groups of women with preterm birth with and without PPROM and those with a normal pregnancy. The incidence of dysbiosis combined with local inflammation was higher in women with spontaneous onset of labor (p=5.02×10^-15) and with PPROM (p=2.01×10^-15). Normocenosis was significantly more common in women with a normal pregnancy compared to those with spontaneous onset of labor (p=3.3×10^-18) and with PPROM (p=1.2×10^-21).

Conclusion: Dysbiotic disorders without local inflammation are not significant prognostic factors for preterm births. To accurately predict this risk, a comprehensive assessment of microbiocenosis and local inflammation in the vagina should be performed.