Exploring Plasma-Level Gut Microbiota Mediators and Pro-Inflammatory Markers in Pregnant Women with Short Cervix and Gestational Diabetes Mellitus

The composition of the gut microbiota (GM) undergoes significant changes during pregnancy, influenced by metabolic status, energy homeostasis, fat storage, and hormonal and immunological modifications. Moreover, dysbiosis during pregnancy has been associated with preterm birth, which is influenced by factors such as cervical shortening, infection, inflammation, and oxidative stress. However, dysbiosis also affects the levels of lipopolysaccharide-binding protein (LBP), short-chain fatty acids (SCFAs), and free fatty acids (FFA) in other tissues and the bloodstream. In this study, we investigated the plasmatic levels of some pro-inflammatory cytokines, such as matrix metalloproteinases-8 (MMP-8), interleukin-8 (IL-8), heat shock protein 70 (Hsp70), and microbial markers in pregnant women with a short cervix (≤25 mm) compared to those with normal cervical length (>25 mm). We examined the differences in the concentration of these markers between the two groups, also assessing the impact of gestational diabetes mellitus. Understanding the relationship between GM dysbiosis, inflammatory mediators, and cervical changes during pregnancy may contribute to the identification of potential biomarkers and therapeutic targets for the prevention and management of adverse pregnancy outcomes, including preterm birth.

Preterm Birth Among Intrapartum Cesarean Deliveries at Public Hospitals in Southern Ethiopia: A Multicenter Retrospective Analysis of Risk Factors

Purpose

Although the underlying causes for preterm birth are thought to be multifactorial irrespective of delivery mode, no study investigated its risk factors amongst cesarean deliveries (CD). Thus, we aimed to identify potential risk factors for the occurrence of preterm birth (PTB) among intrapartum CD.

Methods

Data from 1659 singleton intrapartum CDs were retrospectively recruited using medical records and an obstetric database. Gestational age was calculated using the last menstrual period (LMP) and ultrasound report of early onset pregnancy. A multivariable logistic regression analysis was performed to identify potential risk factors associated with PTB. Odds ratios (ORs) and 95% confidence intervals (95% CI) were used. Statistical analysis was performed using SPSS version 26.0.

Results

In this study, the prevalence of PTB among intrapartum CD was 6.1% (95% CI: 4.9, 7.2%). In the multivariable logistic regression model; grand parity ≥5 (adjusted odds ratio (AOR) = 2.43, 95% CI: 1.72-4.73), maternal age <20 years (AOR=2.63, 95% CI, 1.03-6.71), maternal age ≥35 years (AOR=3.83, 95% CI, 1.49-5.35), cesarean section scar ≥2 (AOR=4.86, 95% CI: 2.68-8.94), antepartum hemorrhage (AOR=4.37, 95% CI: 2.22-8.63), pregnancy-induced hypertension (AOR=2.92, 95% CI: 1.41-6.04), and premature rupture of membranes (AOR=4.56; 95% CI: 1.95-10.65) were significantly associated with PTB.

Conclusion

The current study showed an association between PTB and a multitude of obstetric variables, including grand parity ≥5, CS scar ≥2, antepartum hemorrhage, pregnancy-induced hypertension, and premature rupture of the membrane. Understanding these factors could help to implement improved quality of obstetric and neonatal care to increase survival and reduce morbidity among preterm birth.

Vaginal Microbiome in Pregnant Women with and without Short Cervix

Cervical shortening is a recognised risk factor for pre-term birth. The vaginal microbiome plays an essential role in pregnancy and in maternal and foetal outcomes. We studied the vaginal microbiome in 68 women with singleton gestation and a cervical length ≤25 mm and in 29 pregnant women with a cervix >25 mm in the second or early third trimester. Illumina protocol 16S Metagenomic Sequencing Library Preparation was used to detail amplified 16SrRNA gene. Statistical analyses were performed in R environment. Firmicutes was the phylum most represented in all pregnant women. The mean relative abundance of Proteobacteria and Actinobacteriota was higher in women with a short cervix. Bacterial abundance was higher in women with a normal length cervix compared to the group of women with a short cervix. Nonetheless, a significant enrichment in bacterial taxa poorly represented in vaginal microbiome was observed in the group of women with a short cervix. Staphylococcus and Pseudomonas, taxa usually found in aerobic vaginitis, were more common in women with a short cervix compared with the control group, while Lactobacillus iners and Bifidobacterium were associated with a normal cervical length. Lactobacillus jensenii and Gardenerella vaginalis were associated with a short cervix.

Study protocol to quantify the genetic architecture of sonographic cervical length and its relationship to spontaneous preterm birth

INTRODUCTION

A short cervix (cervical length <25 mm) in the midtrimester (18-24 weeks) of pregnancy is a powerful predictor of spontaneous preterm delivery. Although the biological mechanisms of cervical change during pregnancy have been the subject of extensive investigation, little is known about whether genes influence the length of the cervix, or the extent to which genetic factors contribute to premature cervical shortening. Defining the genetic architecture of cervical length is foundational to understanding the aetiology of a short cervix and its contribution to an increased risk of spontaneous preterm delivery.

METHODS/ANALYSIS

The proposed study is designed to characterise the genetic architecture of cervical length and its genetic relationship to gestational age at delivery in a large cohort of Black/African American women, who are at an increased risk of developing a short cervix and delivering preterm. Repeated measurements of cervical length will be modelled as a longitudinal growth curve, with parameters estimating the initial length of the cervix at the beginning of pregnancy, and its rate of change over time. Genome-wide complex trait analysis methods will be used to estimate the heritability of cervical length growth parameters and their bivariate genetic correlation with gestational age at delivery. Polygenic risk profiling will assess maternal genetic risk for developing a short cervix and subsequently delivering preterm and evaluate the role of cervical length in mediating the relationship between maternal genetic variation and gestational age at delivery.

ETHICS/DISSEMINATION

The proposed analyses will be conducted using deidentified data from participants in an IRB-approved study of longitudinal cervical length who provided blood samples and written informed consent for their use in future genetic research. These analyses are preregistered with the Center for Open Science using the AsPredicted format and the results and genomic summary statistics will be published in a peer-reviewed journal.

Identification of Vaginal Microbial Communities Associated with Extreme Cervical Shortening in Pregnant Women

The vaginal microbiota plays a critical role in pregnancy. Bacteria from Lactobacillus spp. are thought to maintain immune homeostasis and modulate the inflammatory responses against pathogens implicated in cervical shortening, one of the risk factors for spontaneous preterm birth. We studied vaginal microbiota in 46 pregnant women of predominantly Caucasian ethnicity diagnosed with short cervix (<25 mm), and identified microbial communities associated with extreme cervical shortening (≤10 mm). Vaginal microbiota was defined by 16S rRNA gene sequencing and clustered into community state types (CSTs), based on dominance or depletion of Lactobacillus spp. No correlation between CSTs distribution and maternal age or gestational age was revealed. CST-IV, dominated by aerobic and anaerobic bacteria different than Lactobacilli, was associated with extreme cervical shortening (odds ratio (OR) = 15.0, 95% confidence interval (CI) = 1.56–14.21; p = 0.019). CST-III (L. iners-dominated) was also associated with extreme cervical shortening (OR = 6.4, 95% CI = 1.32–31.03; p = 0.02). Gestational diabetes mellitus (GDM) was diagnosed in 10/46 women. Bacterial richness was significantly higher in women experiencing this metabolic disorder, but no association with cervical shortening was revealed by statistical analysis. Our study confirms that Lactobacillus-depleted microbiota is significantly associated with an extremely short cervix in women of predominantly Caucasian ethnicity, and also suggests an association between L. iners-dominated microbiota (CST III) and cervical shortening.

[New methods for preterm birth prediction: the PAMG-1 test]

BACKGROUND

The aim of this study was to assess the efficacy of PAMG-1 test (placental alpha microglobulin-1) in cervicovaginal secretions collected immediately following transvaginal ultrasound (TVUS) of women with signs and symptoms of preterm labor (PTL), clinically intact membranes and cervical length between 15 and 30 mm for the prediction of imminent spontaneous delivery (within 7 days of testing), as well as delivery <34 weeks of gestation.

METHODS

Performing PAMG-1 test in 79 women with singleton pregnancy (240/7 -336/7 weeks' gestation) reporting signs and symptoms indicative of PTL and cervical length <30 mm.

RESULTS

For PTB prediction risk within 7 days of testing in pregnant women with cervicale length between 15-30 mm sensitivity is 100% and specificity is 94%. Positive predictive value (PPV) is 77% and negative predictive value (NPV) is 100%. For delivery prediction <34 weeks of gestation sensitivity decreased from 100% to 67% and specificity from 94% to 89%, PPV is 55% and NPV 93%.

CONCLUSIONS

The inaccuracy of traditional methods, including biophysical tests, biochemical markers, or the combination of both, for assessing the risk of spontaneous preterm birth in patients presenting with symptoms of PTL often leads to unnecessary admission and administration of corticosteroids and tocolytics. The PAMG-1 test demonstrated high efficacy in identifying women at risk of imminent PTL within 7 days of testing, despite being performed immediately after TVUS. High NPV can prevent improper admission and unnecessary therapies for mother and fetus.

Arabin cervical pessary to prevent preterm birth in twin pregnancies with short cervix

A retrospective study was conducted to evaluate the effect of Arabin cervical pessary in twin pregnancies with cervical length (CL)  <25 mm between 21 and 31 weeks. Forty patients receiving pessary were matched with 40 controls without pessary. They were matched for gestational age (GA) at admission and CL. GA at delivery, delivery before 36, 34 and 32 weeks, latency between detection of short cervix and delivery, and duration of hospital admission were compared between groups. Women with the pessary delivered at higher GA compared to controls (35 vs. 33 weeks, p = 0.02). Cervical pessary significantly reduced the incidence of delivery  <36 and  < 34 weeks (p < 0.05), but not before 32 weeks. Interval between detection of short cervix and delivery was longer in the pessary group and duration of hospital admission was shorter (p = 0.03) compared to women without pessary.

A comparison of ultrasonic measurement techniques for the maternal cervix in the second trimester

Introduction: The appropriate ultrasound technique to assess the maternal cervical length in women at low risk of preterm birth is yet to be established. This study aimed to determine the accuracy of different ultrasound approaches for measuring the maternal cervix in patients between 17 and 22 weeks gestation. Methods: The prospective study recruited 50 patients who were at a low risk of preterm birth. All measurements were acquired by one operator who was blind to the measurements being acquired in all approaches. The cervical length was registered using the transabdominal approach with a full and empty bladder, the transperineal approach and the transvaginal. The transvaginal approach was used as the reference measurement. Results: The transabdominal full bladder, post void, transperineal and transvaginal measurements were obtainable in 50, 49, 45 and 50 participants respectively. The transabdominal post void measurements showed a bias of -0.06 mm from perfect agreement with transvaginal. The transperineal measurements showed a bias of -0.16 mm. The transabdominal full bladder measurements were positively biased by 14.05 mm (p < 0.05). All transabdominal post void cervical lengths of 30 mm or greater registered a transvaginal cervical length greater than 25 mm in this study. Conclusion: The cervix should not be assessed in the transabdominal approach with a full maternal bladder due to overestimation of cervical length. Transvaginal cervical length can be reproduced accurately by post void transabdominal cervical length in most cases. Transperineal cervical length should be considered if transvaginal cervical length is contraindicated.