Infectious and immunologic mechanisms of preterm birth in cervical insufficiency: A retrospective cohort study

Background. Cervical insufficiency, often associated with genital infections, remains one of the leading causes of extremely preterm and early preterm births. Since cervicovaginal infections change the antimicrobial properties of cervical mucus, studies of local immunity can offer new insights into the pathogenesis of this pregnancy complication and help predict preterm birth.
Objective. To examine a local immune response in the cervical mucus of pregnant women with cervical insufficiency that leads to preterm birth.
Methods. A retrospective cohort study of 106 pregnant women with cervical insufficiency was conducted. These women were diagnosed with cervical insufficiency according to the clinical guidelines (Cervical Insufficiency, 2021). A microscopic and biomolecular analysis of vaginal and cervical material was performed for all patients. Additionally, the following parameters were estimated in the cervical mucus of 58 randomly selected women: total white blood cell count and functional activity and viability of neutrophils, as well as the levels of macrophage inflammatory protein 1β, high-mobility group protein B1, and matrix metalloproteinase-8. A statistical analysis of the results was performed retrospectively, depending on obstetric outcomes: premature and term births. The obtained data were statistically processed using the SPSS software (version 25.0, IBM, USA). Differences in parameter values between the groups were considered statistically significant at p < 0.05.
Results. Cervicovaginal infections in women with cervical insufficiency were detected in 84.9% of cases in the preterm birth group and in 57.5% of cases in the term birth group (p = 0.002). In both groups, cervicitis was found to be prevalent. In the immunological study of cervical mucus, the group with cervical insufficiency leading to preterm birth differed most significantly in the number of neutrophil extracellular traps, as well as in the levels of macrophage inflammatory protein 1β and high-mobility group protein B1.
Conclusion. Cervicovaginal infections constitute a risk factor for preterm birth. In patients with cervical insufficiency, changes in the local immunity markers of cervical mucus can serve as predictors of preterm birth.

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