Unmasking Preterm Birth Risks: Role of Cervicovaginal Microbiota and Cervical Shortening, study finds
Preterm delivery is one of the primary causes of newborn death, and it is linked to early multiorgan system disorders as well as several long-term neurodevelopmental, familial, and socioeconomic issues. According to certain research, 40-50% of premature deliveries are caused by pathogenic germs that ascend from the vagina and infect the placenta, fetal membranes, cervix, or uterine cavity.
A retrospective cross-sectional study was conducted in the Perinatology Clinic of Ankara City Bilkent Hospital to determine whether the cervicovaginal (CV) microbiota during pregnancy differs between the main obstetric conditions that can cause prematurity, such as TPL, PPROM, or CIS, and to assess the relationship between the presence of significant CV pathogenic microorganisms in culture associated with these obstetric pathologies and compound adverse perinatal outcomes (CAPO).
The research comprised 665 CV culture findings collected during hospitalization from pregnant women hospitalized to perinatology outpatient clinics with diagnoses of TPL, PPROM, or CIS (history, examination, or ultrasound) who did not have any further obstetric problems.
The majority of pregnant women with pathogenic microorganism-dominant CVF tested positive for Candida species (194/234, 82.9%). Candida albicans (97/194, 50%) and Candida glabrata (78/194, 40.2%) were the most common candida species found.
Gardnerella vaginalis (13/40, 32.5%) and Escherichia coli (11/40, 27.5%) were the most often found bacteria in areas with high bacterial proliferation.
Pregnant women with bacterial CVF had the shortest CxL (24.47±9.52 mm). In bacterial CVFs, the median gestational age (GW) at delivery was 34 weeks, with the greatest preterm birth rate (p = 0.024) and lowest birth weight (p = 0.011).
Although there was no difference in NICU stay across the three CVF groups, CAPO was greatest (52.5%) in pregnancies with bacterial CVF.
This research found that preterm delivery and CAPO rates were greatest in pregnancies with bacterial dominated CVF, whereas birth weight was lowest.
The shorter the CxL at the time of culture sample, the more common CAPO was. The determination of a CxL cut-off value of 28.5 mm (AUC: 0.763) in this research provides a new viewpoint on assessing preterm birth risk, especially in pregnancies with non-normal CVF.
The American College of Obstetricians and Gynecologists (ACOG) recommends a short cervix of <25 mm before 24 weeks of gestation . However, the 28.5 mm cut-off has moderate sensitivity and specificity (70.7% and 71.1%, respectively), indicating its potential as an early warning parameter rather than a definitive diagnostic value.
The bacterial CVF group had the greatest CAPO rate, with Gardnerella vaginalis (13/40, 32.5%) being the most often seen growth in this research.
Escherichia coli is the most prevalent microbiological agent in urinary tract infections and also plays an essential role in genital tract infections, since it is usually seen in bacterially dominated CVFs.
When evaluating the study's results, it is necessary to consider the possible influence of future therapeutic treatments such as cervical cerclage, pessary insertion, or prenatal corticosteroid (ACS) injection on obstetric and neonatal outcomes.
The author proposed that if therapies such as cerclage or pessary were subsequently used to mechanically maintain the cervix, they might have altered the course of cervical shortening, thereby delaying delivery and lowering preterm birth-related problems.
The study's limitations include a retrospective and single-center design.
This research underscores the significance of cardiovascular culture sample in pregnant women at risk of premature birth.
Major points –
• Study Focus: The research evaluated the cervicovaginal microbiota (CVF) in pregnant women at risk of preterm birth (due to threatened preterm labor, preterm premature rupture of membranes, or cervical insufficiency) and assessed the link between pathogenic microorganism growth in CV cultures and adverse perinatal outcomes (CAPO).
• Key Findings: Bacterial-dominated CVFs were associated with the highest rates of preterm birth, lowest birth weights, and the highest frequency of composite adverse perinatal outcomes (CAPO), compared to candidal and normal (Lactobacillus-dominated) CVFs.
• Cervical Length as a Predictor: A cervical length (CxL) cut-off of 28.5 mm was identified as having good sensitivity and specificity for predicting adverse perinatal outcomes in women with non-normal (bacterial or candidal) CVFs.
• Clinical Implications: Monitoring both cervical length and CVF composition in pregnant women at risk of preterm delivery may improve prediction and management of adverse perinatal outcomes, emphasizing the importance of integrated anatomical and microbiological assessment.
Reference –
Okutucu G, Tanacan A, Bayraktar N, Ozdal BB, Babayigit EB, Dinc B, Kara O, Sahin D. The intersection of cervicovaginal microbiota and cervical length in predicting adverse perinatal outcomes at preterm birth risk. BMC Pregnancy Childbirth. 2025 Oct 3;25(1):1011. doi: 10.1186/s12884-025-08201-y. PMID: 41044524; PMCID: PMC12495860.
