Abstract

Spontaneous Preterm Birth (SPB) is the most common form of Preterm Birth (PB). Although historically linked to cervical insufficiency, Ascending Bacterial Infection (ABI) is now the most frequent cause of SPB before 34 weeks, driven by vaginal dysbiosis and cervical inflammation. Vaginal dysbiosis, characterized by the loss of protective Lactobacillus and the predominance of bacteria such as Gardnerella or Prevotella, triggers a local inflammatory response with the release of cytokines (IL-1β, IL-6, TNF-α) and metalloproteinases (MMP-8, MMP-9). These factors degrade the extracellular matrix of the cervix and promote pathological cervical ripening. Pathogens like Streptococcus agalactiae and Escherichia coli also release enzymes that degrade the cervical matrix and trigger SPB. Cervical cerclage, traditionally for mechanical issues, offers a dual benefit: An anatomical barrier against microbial ascent and a modulator of local inflammation. Experimental studies show it prevents intrauterine infection and reduces pro-inflammatory cytokines. Clinical research demonstrates a lower incidence of SPB and histological chorioamnionitis in women with a history of SPB due to ABI who receive preventive cerclage in the first trimester. Using monofilament suture is recommended to better preserve the vaginal microbiome. Cerclage is emerging as a comprehensive, personalized strategy to prevent PB linked to ascending cervicovaginal infection and inflammation.

Keywords:Ascending bacterial infection; Spontaneous preterm labor; Cerclage and ascending infection