Abstract: Objective To investigate the effects of reproductive tract Group B streptococcus (GBS) colonization in genital tract on vaginal microecology, serum inflammatory factors and maternal and infant outcomes in late pregnant women. To provide a basis for GBS screening and prevention in pregnant women. Method The clinical data of 6010 cases late pregnant women who delivered in Baoshan People's Hospital from January 2022 to December 2024 and underwent vaginal secretions GBS detection were retrospectively analyzed. According to the GBS test results, the patients were divided into GBS positive group and GBS negative group. The baseline data, vaginal microecological indexes, serum inflammatory factors and maternal and infant outcomes were compared between the two groups. Multivariate logistic regression was used to analyze the influencing factors of GBS colonization in genital tract of late pregnant women. Result Among the 6010 cases late pregnant women, 253 cases were positive for GBS colonization, with a positive rate of 4.21%. The proportions of gestational diabetes mellitus and, thyroid dysfunction, vaginal cleanliness grade Ⅲ-Ⅳ, pH value >4.5, and the distribution of vaginal microbiota in GBS positive group were higher than those in GBS negative group (all P<0.05); The levels of C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), procalcitonin (PCT) in GBS positive group were higher than those in GBS-negative group (all P<0.05) . The incidence rates of neonatal respiratory distress syndrome, hyperbilirubinemia, suppurative meningitis and neonatal GBS infection were higher than those in GBS-negative group (P<0.05). Conclusion GBS colonization in genital tract can cause vaginal microecological imbalance, aggravate inflammatory reaction, and increase the risk of adverse maternal and infant outcomes in late pregnant women.

Key words: Late pregnancy, Group B streptococcus, Vaginal microecology, Inflammatory factors, Maternal and infant outcomes