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THE IMPORTANCE OF VAGINAL MICROFLORA IN THE PATHOGENESIS OF
PREMATURE RUPTURE OF MEMBRANES
Ne`matova Handona,
Mukhitdinova Tukhtakhon Kadirovna,
Yuldasheva Ozoda Sobirovna.
2nd Department of Obstetrics and Gynecology,
Andijan State Medical Institute, Uzbekistan
ABSTRACT:
Premature rupture of membranes (PROM) remains a significant obstetric
complication, contributing to neonatal morbidity and maternal infections. Emerging evidence
suggests that alterations in the vaginal microflora play a critical role in the pathogenesis of
PROM. This prospective, multicenter observational study aimed to evaluate the composition of
vaginal microflora in pregnant women and its association with PROM. A total of 500 pregnant
women, including 250 cases with PROM and 250 gestational age–matched controls, were
enrolled between January 2018 and December 2020. Vaginal swabs were analyzed using culture
methods and molecular techniques (16S rRNA sequencing) to characterize the microflora [1].
Results indicated a significant association between bacterial vaginosis–related organisms (e.g.,
Gardnerella vaginalis, Atopobium vaginae) and the occurrence of PROM, with an observed
disruption in Lactobacillus-dominated flora. Multivariate logistic regression demonstrated that an
abnormal vaginal microflora was an independent predictor of PROM (OR 2.8, 95% CI 1.9–4.2, p
< 0.001). Our findings underscore the need for early screening and targeted interventions to
restore normal vaginal flora, which may reduce the incidence of PROM and its associated
complications [2].
Keywords:
Vaginal microflora, premature rupture of membranes, PROM, bacterial vaginosis,
obstetric infection, 16S rRNA sequencing
INTRODUCTION
Background - Premature rupture of membranes (PROM), defined as the rupture of fetal
membranes before the onset of labor at term, poses significant risks to both the mother and the
neonate. When PROM occurs before 37 weeks of gestation (preterm PROM), the risks are
further compounded by prematurity-related complications. A growing div of literature has
linked alterations in the vaginal microflora to the pathogenesis of PROM. A normal vaginal
microbiome is typically dominated by Lactobacillus species, which help maintain a low pH and
inhibit pathogenic bacterial colonization. In contrast, dysbiosis—characterized by the
overgrowth of anaerobic bacteria such as Gardnerella vaginalis and Atopobium vaginae—has
been implicated in the development of bacterial vaginosis, a known risk factor for PROM [3].
Rationale - The “ascending infection” theory posits that the migration of pathogenic bacteria
from the lower genital tract into the uterine cavity can weaken the fetal membranes and trigger
premature rupture. Despite numerous studies investigating the microbial etiology of PROM, the
specific roles of individual bacterial species and the overall composition of the vaginal
microflora in its pathogenesis remain incompletely understood. Identifying key microbial factors
could pave the way for preventive strategies, including probiotic or antibiotic interventions
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aimed at restoring a healthy vaginal microbiome [4].
Objective - This study was designed to: Characterize the vaginal microflora in pregnant women
with and without PROM. Determine the association between specific microbial profiles and the
incidence of PROM. Evaluate whether alterations in the vaginal microflora serve as an
independent risk factor for PROM after adjusting for known confounders.
MATERIALS AND METHODS
Study Design and Setting - A prospective, multicenter observational study was conducted from
January 2018 to December 2020 at three tertiary obstetric centers. The study was approved by
the Institutional Review Boards of all participating institutions, and written informed consent
was obtained from all participants.
Participants - A total of 500 pregnant women were enrolled and divided into two groups: PROM
Group (n = 250): Pregnant women diagnosed with PROM before the onset of labor, confirmed
by sterile speculum examination and amniotic fluid tests. Control Group (n = 250): Gestational
age–matched pregnant women with intact membranes. Inclusion Criteria: Singleton pregnancy.
Gestational age between 28 and 37 weeks. No antibiotic treatment in the two weeks preceding
enrollment. Exclusion Criteria: Multiple gestations. Pre-existing immunosuppressive conditions.
History of cervical cerclage or uterine anomalies [5].
Data Collection - Vaginal swabs were collected from all participants at the time of enrollment
using sterile techniques. Samples were processed for: Culture Analysis: Identification of aerobic
and anaerobic bacteria using standard microbiological methods. Molecular Analysis: DNA
extraction followed by 16S rRNA gene sequencing to characterize bacterial community
composition. In addition, clinical data, including maternal age, div mass index (BMI), obstetric
history, and known risk factors for PROM, were recorded using a standardized questionnaire [6].
Outcome Measures - The primary outcome was the association between abnormal vaginal
microflora (defined as a deviation from a Lactobacillus-dominated community) and PROM.
Secondary outcomes included the identification of specific bacterial taxa linked to PROM and
the evaluation of neonatal outcomes (birth weight, Apgar scores, and NICU admissions).
Statistical Analysis - Statistical analysis was performed using SPSS version 27.0. Continuous
variables were expressed as mean ± standard deviation (SD) and compared using the Student’s t-
test, while categorical variables were compared using the chi-square test. Multivariate logistic
regression was used to adjust for confounders and determine the independent effect of vaginal
microflora on the risk of PROM. A p-value <0.05 was considered statistically significant.
RESULTS
Demographic and Baseline Characteristics - The mean maternal age was 29.8 ± 4.7 years in the
PROM group and 29.5 ± 4.5 years in the control group (p = 0.42). Baseline BMI, parity, and
gestational age at enrollment were comparable between groups (see Table 1).
Table 1. Baseline Characteristics of the Study Population (n = 500)
Variable
PROM Group (n =
250)
Control Group (n =
250)
p-
value
Mean Age (years)
29.8 ± 4.7
29.5 ± 4.5
0.42
BMI (kg/m²)
25.1 ± 3.2
24.9 ± 3.0
0.55
Primiparity (%)
48%
50%
0.68
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Gestational Age at Enrollment
(weeks)
32.1 ± 2.3
32.3 ± 2.4
0.30
Vaginal Microflora Composition - Culture and 16S rRNA sequencing revealed significant
differences in the vaginal microbial communities between the two groups: Lactobacillus
Dominance: 72% of controls exhibited a Lactobacillus-dominated flora compared with 45% of
the PROM group (p < 0.001). Bacterial Vaginosis–Associated Bacteria: The PROM group
showed a higher prevalence of Gardnerella vaginalis, Atopobium vaginae, and Mobiluncus spp.
(p < 0.001). Diversity Index: Shannon diversity index was significantly higher in the PROM
group, indicating greater microbial diversity and dysbiosis (p < 0.01).
Association with PROM - Multivariate logistic regression analysis adjusted for maternal age,
BMI, and smoking status demonstrated that an abnormal vaginal microflora (non-Lactobacillus
dominant) was an independent predictor of PROM (OR 2.8, 95% CI 1.9–4.2, p < 0.001).
Additionally, the presence of Gardnerella vaginalis was strongly associated with PROM (OR 3.1,
95% CI 2.0–4.8, p < 0.001).
Neonatal Outcomes - Neonatal outcomes were adversely affected in the PROM group: Birth
Weight: The mean birth weight was significantly lower in the PROM group (2850 ± 420 g)
compared with controls (3050 ± 380 g, p = 0.001). Apgar Scores: The 5-minute Apgar score was
marginally lower in neonates born fter PROM (7.6 ± 0.8 vs. 8.1 ± 0.7, p = 0.01). NICU
Admissions:
NICU admission rates were higher in the PROM group (15% vs. 8%, p = 0.02).
DISCUSSION
Principal Findings - This study confirms that alterations in the vaginal microflora are
significantly associated with the occurrence of PROM. Pregnant women with PROM were more
likely to have a disrupted vaginal ecosystem, characterized by reduced Lactobacillus dominance
and an overgrowth of bacterial vaginosis–associated organisms. These dysbiotic changes were
independently associated with an increased risk of PROM even after adjusting for known
confounding factors [7].
Pathophysiological Implications - The integrity of the fetal membranes is believed to be
compromised by ascending infections from the lower genital tract. In a healthy vaginal
environment, Lactobacillus species produce lactic acid and bacteriocins that inhibit pathogenic
bacteria. Dysbiosis, on the other hand, creates an inflammatory milieu that may weaken the
collagen structure of the fetal membranes, predisposing them to premature rupture. Our findings
support the hypothesis that targeting vaginal dysbiosis could serve as a preventive strategy
against PROM.
Clinical Implications - Early screening for vaginal dysbiosis during pregnancy may identify
women at higher risk for PROM. Interventions such as probiotic therapy, targeted antibiotic
treatment, or vaginal microbiome modulation could potentially restore a healthy microflora and
reduce the incidence of PROM. Additionally, understanding the microbial profiles associated
with PROM can inform clinical decision-making and prompt closer monitoring of at-risk
pregnancies.
Comparison with Previous Studies - Our results are consistent with previous studies linking
bacterial vaginosis and abnormal vaginal microflora to PROM. However, the use of advanced
molecular techniques in this study allowed for a more detailed characterization of the microbial
community, underscoring the importance of microbial diversity as a factor in PROM
pathogenesis. The strong association of Gardnerella vaginalis with PROM aligns with the
findings of other recent investigations.
Limitations - This study has several limitations: Observational Design: The design precludes
establishing a causal relationship between microflora alterations and PROM. Single-Time Point
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Sampling: Microbial profiles were assessed at enrollment, and longitudinal changes were not
evaluated. Potential Confounders: Although multivariate analysis was performed, residual
confounding cannot be entirely ruled out.
Future Directions - Future research should focus on longitudinal studies to monitor changes in
the vaginal microflora throughout pregnancy and assess the impact of therapeutic interventions
on PROM risk. Randomized controlled trials evaluating probiotic or antimicrobial therapies
aimed at restoring normal vaginal flora are warranted. Moreover, investigations into the
molecular mechanisms linking microbial dysbiosis and membrane integrity may provide further
insights into PROM pathogenesis.
CONCLUSION
Our findings indicate that abnormal vaginal microflora, particularly the reduction of
Lactobacillus dominance and overrepresentation of bacterial vaginosis–associated organisms, is
significantly associated with an increased risk of PROM. Early identification and targeted
correction of vaginal dysbiosis may represent a promising strategy to reduce the incidence of
PROM and improve perinatal outcomes. This study highlights the importance of integrating
microbial diagnostics into prenatal care to identify at-risk pregnancies and tailor preventive
interventions accordingly.
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