Prediction of spontaneous preterm birth in women with cervical insufficiency: Comprehensive analysis of multiple proteins in amniotic fluid

A systematic review of prediction models for spontaneous preterm birth in singleton asymptomatic pregnant women with risk factors

Backgrounds

Spontaneous preterm birth (SPB) is a global problem. Early screening, identification, and prevention in asymptomatic pregnant women with risk factors for preterm birth can help reduce the incidence and mortality of preterm births. Therefore, this study systematically reviewed prediction models for spontaneous preterm birth, summarised the model characteristics, and appraised their quality to identify the best-performing prediction model for clinical decision-making.

Methods

PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, China Biology Medicine disc, VIP Database, and Wanfang Data were searched up to September 27, 2021. Prediction models for spontaneous preterm births in singleton asymptomatic pregnant women with risk factors were eligible for inclusion. Six independent reviewers selected the eligible studies and extracted data from the prediction models. The findings were summarised using descriptive statistics and visual plots.

Results

Twelve studies with twelve developmental models were included. Discriminative performance was reported in 11 studies, with an Area Under the Curve (AUC) ranging from 0.75 to 0.95. The AUCs of the seven models were greater than 0.85. Cervical length (CL) is the most commonly used predictor of spontaneous preterm birth. A total of 91.7% of the studies had a high risk of bias in the analysis domain, mainly because of the small sample size and lack of adjustment for overfitting.

Conclusion

The accuracy of the models for spontaneous preterm births in singleton asymptomatic women with risk factors was good. However, these models are not widely used in clinical practice because they lack replicability and transparency. Future studies should transparently report methodological details and consider more meaningful predictors with new progress in research on preterm birth.

Degree of expression of inflammatory proteins in the amniotic cavity, but not prior obstetric history, is associated with the risk severity for spontaneous preterm birth after rescue cerclage for cervical insufficiency

PROBLEM

To examine whether the severity of spontaneous preterm birth (SPTB) risk after rescue cerclage for acute cervical insufficiency (CI) is linked to the degree of inflammatory response in the amniotic fluid (AF) based on the concentrations of various inflammatory proteins and prior obstetric history.

METHOD OF STUDY

We conducted a retrospective cohort study of 65 singleton pregnant women (17-25 weeks) who underwent rescue cerclage following the diagnosis of acute CI and were subjected to amniocentesis. EN-RAGE, IL-6, IL-8, and IP-10 as inflammatory mediators and kallistatin, MMP-2/8, and uPA as extracellular matrix remodeling-related molecules were assayed in the AF using ELISA. The level of each inflammatory mediator was divided into quartiles.

RESULTS

Intra-amniotic inflammation (IAI; AF IL-6 level ≥2.6 ng/mL) was independently associated with SPTB after cerclage placement. The odds of SPTB at < 32 weeks, even after adjusting for confounders, increased significantly with each increasing quartile of baseline AF levels for each inflammatory mediator (p for trend < .05). Kaplan-Meier survival curves showed that the cerclage-to-delivery intervals were significantly shorter as the quartiles of AF EN-RAGE and MMP-8 increased (log-rank test, p < .01 each). Neither previous term birth nor prior PTB was associated with SPTB risk or cerclage-to-delivery interval after rescue cerclage. Multiparous women who experience CI after term birth showed significantly elevated levels of MMP-8 and reduced kallistatin levels in the AF.

CONCLUSION

In patients with CI, SPTB risk (especially risk severity) after rescue cerclage is associated with the degree of the inflammatory response in AF as well as the presence of IAI but not with prior obstetric history.

Prenatal exposure to perfluoroalkyl substances and inflammatory biomarker concentrations

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants that induce immunotoxicity in experimental studies; however, epidemiological evidence-particularly during pregnancy-is scarce. We quantified associations between first trimester plasma perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonate (PFHxS) concentrations and third trimester concentrations of inflammatory biomarkers and determined if these associations were modified by fetal sex.

Methods

We analyzed data from 1411 participants, recruited between 2008 and 2011, in the Maternal-Infant Research on Environmental Chemicals study. Our primary outcome was a composite inflammatory index derived by summing the z-scores of eight proinflammatory biomarkers. Using multivariable linear regression models, we quantified associations between each PFAS and the inflammatory index and individual biomarkers. We quantified the effects of the PFAS mixture using weighted quantile sum regression, and evaluated effect modification using product terms and sex-stratified models.

Results

Each doubling of PFOA and PFHxS was associated with a 0.38 (95% CI, 0.09, 0.67) and 0.21 (95% CI, 0.01, 0.41) SD increase in the proinflammatory index, respectively. A one-quartile increase in the PFAS mixture was associated with a 0.40 (95% CI, 0.09, 0.71) SD increase in the proinflammatory index. In individual models, we observed positive associations between PFAS and concentrations of monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, and matrix metalloproteinases-9; however, the magnitude and precision varied according to the specific PFAS. Sex-specific findings were identified in few PFAS-biomarker associations.

Conclusions

PFOA, PFOS, and PFHxS, individually and as a mixture, were positively associated with proinflammatory biomarkers during pregnancy.

Extracellular matrix-related and serine protease proteins in the amniotic fluid of women with early preterm labor: Association with spontaneous preterm birth, intra-amniotic inflammation, and microbial invasion of the amniotic cavity

PROBLEM

We aimed to determine whether altered levels of various extracellular matrix (ECM)-related and serine protease proteins in the amniotic fluid (AF) are associated with imminent spontaneous preterm birth (SPTB; ≤7 days) and intra-amniotic inflammation and/or microbial invasion of the amniotic cavity (IAI/MIAC) in women with early preterm labor (PTL).

METHOD OF STUDY

This retrospective cohort study included 252 women with singleton pregnancies undergoing transabdominal amniocentesis who demonstrated PTL (24-31 weeks). The AF was cultured for microorganism detection to characterize MIAC. IL-6 concentrations were determined in the AF samples to identify IAI (≥2.6 ng/mL). The following mediators were measured in the AF samples using ELISA: kallistatin, lumican, MMP-2, SPARC, TGFBI, and uPA.

RESULTS

Kallistatin, MMP-2, TGFBI, and uPA levels were significantly higher and SPARC and lumican levels were significantly lower in the AF of women who spontaneously delivered within 7 days than in the AF of those who delivered after 7 days; the levels of the first five mediators were independent of baseline clinical variables. In the multivariate analysis, elevated levels of kallistatin, MMP-2, TGFBI, and uPA and low levels of lumican and SPARC in the AF were significantly associated with IAI/MIAC and MIAC, even after adjusting for the gestational age at sampling. The areas under the curves of the aforementioned biomarkers ranged from 0.58 to 0.87 for the diagnoses of each of the corresponding endpoints.

CONCLUSION

ECM-related (SPARC, TGFBI, lumican, and MMP-2) and serine protease (kallistatin and uPA) proteins in the AF are involved in preterm parturition and regulation of intra-amniotic inflammatory/infectious responses in PTL.

Development of risk prediction models for preterm delivery in a rural setting in Ethiopia

Background

Preterm birth complications are the leading causes of death among children under five years. However, the inability to accurately identify pregnancies at high risk of preterm delivery is a key practical challenge, especially in resource-constrained settings with limited availability of biomarkers assessment.

Methods

We evaluated whether risk of preterm delivery can be predicted using available data from a pregnancy and birth cohort in Amhara region, Ethiopia. All participants were enrolled in the cohort between December 2018 and March 2020. The study outcome was preterm delivery, defined as any delivery occurring before week 37 of gestation regardless of vital status of the foetus or neonate. A range of sociodemographic, clinical, environmental, and pregnancy-related factors were considered as potential inputs. We used Cox and accelerated failure time models, alongside decision tree ensembles to predict risk of preterm delivery. We estimated model discrimination using the area-under-the-curve (AUC) and simulated the conditional distributions of cervical length (CL) and foetal fibronectin (FFN) to ascertain whether they could improve model performance.

Results

We included 2493 pregnancies; among them, 138 women were censored due to loss-to-follow-up before delivery. Overall, predictive performance of models was poor. The AUC was highest for the tree ensemble classifier (0.60, 95% confidence interval = 0.57-0.63). When models were calibrated so that 90% of women who experienced a preterm delivery were classified as high risk, at least 75% of those classified as high risk did not experience the outcome. The simulation of CL and FFN distributions did not significantly improve models' performance.

Conclusions

Prediction of preterm delivery remains a major challenge. In resource-limited settings, predicting high-risk deliveries would not only save lives, but also inform resource allocation. It may not be possible to accurately predict risk of preterm delivery without investing in novel technologies to identify genetic factors, immunological biomarkers, or the expression of specific proteins.

The amniotic fluid proteome predicts imminent preterm delivery in asymptomatic women with a short cervix

Preterm birth, the leading cause of perinatal morbidity and mortality, is associated with increased risk of short- and long-term adverse outcomes. For women identified as at risk for preterm birth attributable to a sonographic short cervix, the determination of imminent delivery is crucial for patient management. The current study aimed to identify amniotic fluid (AF) proteins that could predict imminent delivery in asymptomatic patients with a short cervix. This retrospective cohort study included women enrolled between May 2002 and September 2015 who were diagnosed with a sonographic short cervix (< 25 mm) at 16–32 weeks of gestation. Amniocenteses were performed to exclude intra-amniotic infection; none of the women included had clinical signs of infection or labor at the time of amniocentesis. An aptamer-based multiplex platform was used to profile 1310 AF proteins, and the differential protein abundance between women who delivered within two weeks from amniocentesis, and those who did not, was determined. The analysis included adjustment for quantitative cervical length and control of the false-positive rate at 10%. The area under the receiver operating characteristic curve was calculated to determine whether protein abundance in combination with cervical length improved the prediction of imminent preterm delivery as compared to cervical length alone. Of the 1,310 proteins profiled in AF, 17 were differentially abundant in women destined to deliver within two weeks of amniocentesis independently of the cervical length (adjusted p-value < 0.10). The decreased abundance of SNAP25 and the increased abundance of GPI, PTPN11, OLR1, ENO1, GAPDH, CHI3L1, RETN, CSF3, LCN2, CXCL1, CXCL8, PGLYRP1, LDHB, IL6, MMP8, and PRTN3 were associated with an increased risk of imminent delivery (odds ratio > 1.5 for each). The sensitivity at a 10% false-positive rate for the prediction of imminent delivery by a quantitative cervical length alone was 38%, yet it increased to 79% when combined with the abundance of four AF proteins (CXCL8, SNAP25, PTPN11, and MMP8). Neutrophil-mediated immunity, neutrophil activation, granulocyte activation, myeloid leukocyte activation, and myeloid leukocyte-mediated immunity were biological processes impacted by protein dysregulation in women destined to deliver within two weeks of diagnosis. The combination of AF protein abundance and quantitative cervical length improves prediction of the timing of delivery compared to cervical length alone, among women with a sonographic short cervix.

Prediction of emergency cerclage outcomes in women with cervical insufficiency: The role of inflammatory, angiogenic, and extracellular matrix-related proteins in amniotic fluid

OBJECTIVE

We aimed to determine whether various novel inflammatory, angiogenic, and extracellular matrix-related mediators in amniotic fluid (AF) can independently predict emergency cerclage outcomes in women with acute cervical insufficiency (CI).

METHODS

This was a retrospective cohort study conducted among 50 singleton pregnant women (18-25 weeks) who underwent emergency cerclage for CI and were subjected to amniocentesis. The AF samples were assayed for endoglin, endostatin, haptoglobin, insulin-like growth factor-binding protein (IGFBP)-3, -4, kallistatin, lumican, macrophage colony-stimulating factor (M-CSF), pentraxin 3, p-selectin, receptor for advanced glycation end products (RAGE), resistin, transforming growth factor beta-induced (TGFBI), and vitamin D-binding protein (VDBP) levels. Interleukin (IL)-6 levels in the AF were also measured for comparison with potential biomarkers assessed in this study. The primary endpoint was spontaneous preterm delivery (SPTD) at <34 weeks following emergency cerclage.

RESULTS

The AF levels of pentraxin 3, RAGE, and resistin were significantly higher in women who had SPTD at <34 weeks after cerclage placement (pentraxin-3: P = 0.003; RAGE: P = 0.041; and resistin; P = 0.002). In multivariate analysis, elevated AF levels of pentraxin 3 (P = 0.007) and resistin (P = 0.006), but not those of RAGE (P = 0.069), were independently associated with the occurrence of SPTD at <34 weeks after cerclage, following adjustment for baseline clinical variables (e.g., cervical dilation). The area under the curve (AUC) values of AF pentraxin 3, RAGE, and resistin for the prediction of SPTD at <34 weeks were 0.749, 0.669, and 0.770, respectively, which were similar to those of AF IL-6. However, in univariate analyses, no differences in the AF levels of endoglin, endostatin, haptoglobin, IGFBP-3, IGFBP-4, kallistatin, lumican, p-selectin, TGFBI, and VDBP were found to be associated with SPTD at <34 weeks after cerclage placement.

CONCLUSIONS

In women with acute CI, the AF levels of pentraxin 3, RAGE, and resistin could be useful novel biomarkers for predicting SPTD following emergency cerclage. However, the clinical utility of these new biomarkers should be validated in larger multicenter studies.

Inflammation-related immune proteins in maternal plasma as potential predictive biomarkers for rescue cerclage outcome in women with cervical insufficiency

PROBLEM

This study aimed to determine whether various novel plasma mediators of immune regulation associated with inflammation could independently predict the clinical outcome of rescue cerclage in patients with cervical insufficiency (CI).

METHOD OF STUDY

A total of 41 singleton pregnant women (17-25 weeks) who underwent rescue cerclage for CI were retrospectively evaluated. Stored plasma samples were assayed for IGFBP-1, -2, -3, IL-6, latexin, LBP, lipocalin-2, M-CSF, MIP-1α, MMP-8, -9, pentraxin 3, resistin, S100A8, S100A8/A9, thrombospondin-2, TIMP-1, and TNFR2 levels. The primary outcome measures were spontaneous preterm birth (SPTB) at < 28 and < 34 weeks after cerclage placement.

RESULTS

Multivariate Firth's logistic regression analysis revealed that high levels of IGFBP-3 and S100A8/A9, and low levels of MIP-1α were significantly associated with SPTB at < 28 weeks after cerclage placement, whereas only low MIP-1α levels were significantly associated with SPTB at < 34 weeks, even after adjustment for baseline clinical covariates (e.g., cervical dilatation). For the prediction of SPTB at < 28 weeks, the area under the curves (AUC) of IGFBP-3, MIP-1α, and S100A8/A9 were of .686, .691, and .693, respectively. Similarly, the AUC of MIP-1 α was of .659 to predict SPTB at < 34 weeks.

CONCLUSIONS

These findings suggest that plasma IGFBP-3, MIP-1α, and S100A8/A9 can represent noninvasive independent biomarkers for identifying women with CI at high risk for SPTB following rescue cerclage. Nonetheless, further in large, multicenter clinical studies should be performed to confirm the clinical value of these biomarkers.

Elevated midtrimester maternal plasma cytokines and preterm birth in patients with cerclage

BACKGROUND

Cerclage is used for the prevention of spontaneous preterm birth; however, many patients at high risk of spontaneous preterm birth who have a cerclage in place eventually deliver before term. Although inflammation, measured by biomarkers (eg, cytokines), is a known risk factor for preterm delivery, evaluation of inflammation to determine pregnancy outcomes among patients with cerclage is poorly understood.

OBJECTIVE

We sought to examine levels of maternal plasma inflammatory cytokines in the midtrimester among asymptomatic patients with a cervical cerclage (placed for any indication, including history, ultrasound, and examination indications) to evaluate the association between cytokine levels and preterm birth.

STUDY DESIGN

This was a prospective cohort study of singleton, nonanomalous pregnancies who had a cerclage placed at <24 weeks of gestation from 2015 to 2018 at a single tertiary institution. Maternal plasma was collected perioperatively whenever possible. A custom magnetic bead Luminex cytokine assay was used to measure plasma inflammatory cytokine levels from these stored samples. The primary outcome was preterm birth at <37 weeks of gestation. A statistical cut point was calculated for each cytokine level to assess its optimal sensitivity and specificity for spontaneous preterm birth prediction. Patients were classified as having a "high" or "low" result for each cytokine based on this cut point. Receiver operating characteristic curve analysis was performed to estimate sensitivity, specificity, and positive and negative predictive values for spontaneous preterm birth prediction. Cox proportional-hazards regression modeled the association between the number of "high" inflammatory cytokines and gestational age at delivery, adjusting for confounders. Additional analyses were performed on the subgroup of patients with history-indicated cerclage and those with an ultrasound- or examination-indicated cerclage.

RESULTS

A total of 43 patients participated in this study: 20 (46.5%) had spontaneous preterm birth (median, 30.9 weeks of gestation; interquartile range, 28.4-35.0). Plasma samples were collected at a median of 0 (interquartile range, -2 to 17) days concerning cerclage placement and a median of 18 (interquartile range, 13-21) weeks of gestation. Based on the statistical cut point for each cytokine level, 7% of patients had zero, 20.9% had 1, 18.6% had 2, 20.9% had 3, and 32.6% had ≥4 "high" cytokine results. Each additional "high" cytokine level was associated with earlier delivery (hazard ratio, 1.51; 95% confidence interval, 1.25-1.81) even after controlling for ultrasound- or examination-indication for cerclage (hazard ratio, 1.73; 95% confidence interval, 0.95-3.15). The presence of ≥4 "high" cytokine levels was 70% sensitive and 74% specific for predicting spontaneous preterm birth (area under the curve, 0.846; 95% confidence interval, 0.728-0.964; positive predictive value, 70%; negative predictive value, 73.9%).

CONCLUSION

Among patients with a cervical cerclage, elevated midtrimester maternal plasma cytokine profiles were associated with subsequent preterm birth and can estimate the probability of preterm birth. Confirmation and refinement of this noninvasive panel may provide insight into improved selection of individuals who may benefit from cerclage placement and investigation of therapeutic strategies to mitigate midpregnancy inflammation.

Antibody microarray analysis of amniotic fluid proteomes in women with cervical insufficiency and short cervix, and their association with pregnancy latency length

Introduction

This study aimed to investigate amniotic fluid (AF) proteins that were differentially expressed between patients with cervical insufficiency (CI) and asymptomatic short cervix (SCX, ≤ 25 mm), and whether these proteins could be predictive of spontaneous preterm birth (SPTB) in these patients.

Method

This was a retrospective cohort study of 129 singleton pregnant women with CI (n = 80) or SCX (n = 49) at 17 to 26 weeks who underwent amniocentesis. An antibody microarray was used to perform comparative proteomic profiling of AF from matched CI (n = 20) and SCX (n = 20) pregnancies. In the total cohort, an ELISA validation study was performed for 15 candidate proteins of interest. Subgroup analyses of patients with CI and SCX were conducted to evaluate the association between the 15 proteins and SPTB at < 32 weeks of gestation.

Results

Eighty-six proteins showed intergroup differences. ELISA validation confirmed significantly higher levels of AF EN-RAGE, IL-8, lipocalin-2, MMP-9, S100A8/A9, thrombospondin-2, and TNFR2 in patients with CI than in those with SCX. Multivariable analysis showed that increased AF levels of EN-RAGE, S100A8/A9, and uPA were independently associated with SPTB at < 32 weeks in patients with CI; whereas in patients with SCX, high AF levels of APRIL, EN-RAGE, LBP, and TNFR2 were independently associated with SPTB at < 32 weeks.

Conclusions

Multiple AF proteins show altered expression in patients with CI compared with SCX controls. Moreover, several novel mediators involved in inflammation were identified as potential biomarkers for predicting SPTB after the diagnosis of CI and SCX. These results provide new insights into target-specific molecules for targeted therapies to prevent SPTB in patients with CI/SCX.

Elastography and Metalloproteinases in Patients at High Risk of Preterm Labor

Preterm birth (PTB) is the leading cause of perinatal morbidity and mortality. Its etiopathology is multifactorial; therefore, many of the tests contain the assessment of the biochemical factors and ultrasound evaluation of the cervix in patients at risk of preterm delivery. The study aimed at evaluating the socioeconomic data, ultrasound examinations with elastography, plasma concentrations of MMP-8 and MMP-9 metalloproteinases, and vaginal secretions in the control group as well as patients with threatened preterm delivery (high-risk patients). The study included 88 patients hospitalized in the Department of Obstetrics and Pregnancy Pathology, SPSK 1, in Lublin. Patients were qualified to the study group (50) with a transvaginal ultrasonography of cervical length (CL) ≤ 25 mm. The control group (38) were patients with a physiological course of pregnancy with CL > 25 mm. In the study group, the median length of the cervix was 17.49 mm. Elastographic parameters: strain and ratio were 0.20 and 0.83. In the control group, the median length of the cervix was 34.73 mm, while the strain and ratio were 0.20 and 1.23. In the study group, the concentration of MMP-8 in the serum and secretions of the cervix was on average 74.17 and 155.46 ng/mL, but in the control group, it was significantly lower, on average 58.49 and 94.19 ng/mL. The concentration of MMP-9 in both groups was on the same level. Evaluation of the cervical length and measurement of MMP-8 concentration are the methods of predicting preterm delivery in high-risk patients. The use of static elastography did not meet the criteria of a PTB marker.

Antibody microarray analysis of the amniotic fluid proteome for predicting the outcome of rescue cerclage in patients with cervical insufficiency

Little is known about the biomarkers that can identify patient candidates suitable for rescue cerclage procedure. The purpose of the study was to identify novel biomarkers in amniotic fluid (AF) that can predict the outcome of rescue cerclage in patients with cervical insufficiency by using an antibody microarray. This case–control study was conducted using AF samples collected from singleton pregnant women who underwent rescue cerclage following a diagnosis of cervical insufficiency (19–25 weeks). Patients were divided into case (n=20) and control (n=20) groups based on the occurrence of spontaneous preterm delivery (SPTD) at <34 weeks of gestation after cerclage placement. The AF proteomes were analyzed using an antibody microarray for biomarker discovery work. Ten candidate biomarkers of interest were validated by enzyme-linked immunosorbent assay (ELISA). Thirty-one molecules studied showed significant intergroup differences (≥two-fold change in signal intensity). Validation by ELISA confirmed significantly higher levels of a proliferation-inducing ligand (APRIL), S100 calcium-binding protein A8/A9 complex (S100 A8/A9), tissue inhibitors of metalloproteinase-1 (TIMP-1), macrophage inflammatory protein-1α (MIP-1α), and interleukin-8 (IL-8) in women who had SPTD at <34 weeks. Of these, AF S100 A8/A9 and TIMP-1 levels were independent of other potentially confounding factors (e.g., cervical dilatation). S100 A8/A9 had the highest area under the curve (AUC) at 0.857. Using protein–antibody microarray technology, we identified differentially expressed proteins (DEPs) and several novel biomarkers (APRIL, IL-8, MIP-1α, S100 A8/A9, and TIMP-1) in AF from women who had SPTB at <34 weeks after cerclage for cervical insufficiency. These data can provide an insight into the molecular mechanisms underlying SPTD after rescue cerclage in patients with cervical insufficiency.

Macrophage inflammatory protein-1α in amniotic and cervical fluids in spontaneous preterm labor with intact membranes with respect to intra-amniotic inflammation

OBJECTIVE

Macrophage inflammatory protein 1α is a chemokine produced by various immune, epithelial, mesothelial, and fibroblast cells after exposure to bacterial lipopolysaccharide or pro-inflammatory molecules. The primary aim of this study was to determine MIP-1α concentrations in amniotic and cervical fluids from pregnancy with spontaneous preterm labor with intact membranes (PTL) with respect to the presence of intra-amniotic infection (both microbial invasion of the amniotic cavity and intra-amniotic inflammation) and sterile intra-amniotic inflammation (intra-amniotic inflammation alone). The secondary aim was to assess the diagnostic indices of MIP-1α in predicting intra-amniotic infection.

MATERIALS AND METHODS

Seventy-four women with PTL were included in this study. Paired amniotic and cervical fluid samples were obtained using transabdominal amniocentesis and a Dacron polyester swab, respectively. Microbial invasion of the amniotic cavity was diagnosed based on a combination of culture and molecular biology methods. The concentration of IL-6 in the amniotic and cervical fluids was measured using an automated electrochemiluminescence immunoassay method. Intra-amniotic inflammation was defined as an amniotic fluid IL-6 concentration of ≥3000 pg/mL. The MIP-1α concentrations in the samples were assessed using an enzyme-linked immunosorbent assay.

RESULTS

A difference in amniotic fluid MIP-1α was observed among women with intra-amniotic infection, sterile intra-amniotic inflammation, and negative amniotic fluid (infection: median 1779.0 pg/mL; sterile, median 102.7 pg/mL; negative, median 19.9 pg/mL; p < .0001). No difference in the concentrations of MIP-1α was identified in cervical fluid after adjustment for gestational age at sampling (infection: median 77.7 pg/mL, sterile: median 152.7 pg/mL, negative: median 18.0 pg/mL; p = .30). The presence of intra-amniotic infection was associated with elevated MIP-1α concentrations in amniotic fluid (presence: 1779.0 pg/mL vs. absence: 26.3 pg/mL, p < .0001, area under receiver operating characteristic curve = 0.87).

CONCLUSIONS

In PTL pregnancies with the presence of intra-amniotic infection, the concentration of MIP-1α is elevated in amniotic fluid but not in cervical fluid. Amniotic fluid MIP-1α may provide a useful marker for intra-amniotic infection in women with PTL.

Hyaluronidase Impairs Neutrophil Function and Promotes Group B Streptococcus Invasion and Preterm Labor in Nonhuman Primates

Invasive bacterial infections during pregnancy are a major risk factor for preterm birth, stillbirth, and fetal injury. Group B streptococci (GBS) are Gram-positive bacteria that asymptomatically colonize the lower genital tract but infect the amniotic fluid and induce preterm birth or stillbirth. Experimental models that closely emulate human pregnancy are pivotal for the development of successful strategies to prevent these adverse pregnancy outcomes. Using a unique nonhuman primate model that mimics human pregnancy and informs temporal events surrounding amniotic cavity invasion and preterm labor, we show that the animals inoculated with hyaluronidase (HylB)-expressing GBS consistently exhibited microbial invasion into the amniotic cavity, fetal bacteremia, and preterm labor. Although delayed cytokine responses were observed at the maternal-fetal interface, increased prostaglandin and matrix metalloproteinase levels in these animals likely mediated preterm labor. HylB-proficient GBS dampened reactive oxygen species production and exhibited increased resistance to neutrophils compared to an isogenic mutant. Together, these findings demonstrate how a bacterial enzyme promotes GBS amniotic cavity invasion and preterm labor in a model that closely resembles human pregnancy.

Protein Concentrations of Thrombospondin-1, MIP-1β, and S100A8 Suggest the Reflection of a Pregnancy Clock in Mid-Trimester Amniotic Fluid

The development of immunoassays enables more sophisticated studies of the associations between protein concentrations and pregnancy outcomes, allowing early biomarker identification that can improve neonatal outcomes. The aim of this study was to explore associations between selected mid-trimester amniotic fluid proteins and (1) overall gestational duration and (2) spontaneous preterm delivery. A prospective cohort study, including women undergoing mid-trimester transabdominal genetic amniocentesis, was performed in Gothenburg, Sweden, 2008-2016 (n = 1072). A panel of 27 proteins related to inflammation was analyzed using Meso-Scale multiplex technology. Concentrations were adjusted for gestational age at sampling, experimental factors, year of sampling, and covariates (maternal age at sampling, parity (nulliparous/multiparous), smoking at first prenatal visit, and in vitro fertilization). Cox regression analysis of the entire cohort was performed to explore possible associations between protein concentrations and gestational duration. This was followed by Cox regression analysis censored at 259 days or longer, to investigate whether associations were detectable in women with spontaneous preterm delivery (n = 47). Finally, linear regression models were performed to analyze associations between protein concentrations and gestational duration in women with spontaneous onset of labor at term (n = 784). HMG-1, IGFBP-1, IL-18, MIP-1α, MIP-1β, S100A8, and thrombospondin-1 were significantly associated with gestational duration at term, but not preterm. Increased concentrations of thrombospondin-1, MIP-1β, and S100A8, respectively, were significantly associated with decreased gestational duration after the Holm-Bonferroni correction in women with spontaneous onset of labor at term. This adds to the concept of a pregnancy clock, where our findings suggest that such a clock is also reflected in the amniotic fluid at early mid-trimester, but further research is needed to confirm this.

Cervicovaginal fluid cytokines as predictive markers of preterm birth in symptomatic women

Objective

Here, we investigated whether cytokines in the cervicovaginal fluid (CVF) can be predictive markers of preterm birth (PTB).

Methods

A multi-center prospective cohort study was conducted on 59 singleton pregnant women hospitalized for preterm labor (PTL) and/or preterm premature rupture of membranes (pPROM) between 22 weeks and 36 weeks 6 days of gestation from 2014 to 2015. The levels of 13 inflammatory cytokines (macrophage inflammatory protein [MIP]-1α, MIP-1β, tumor necrosis factor [TNF]-α, interleukin [IL]-1β, IL-6, IL-8, IL-17α, granulocyte colony stimulating factor [G-CSF], IL-7, IL-4, IL-5, IL-10, and IL-13) were measured using a multiplex bead-based immunoassay and that of fetal fibronectin (fFN) was measured using enzyme-linked immunosorbent assay (ELISA). Statistical analyses were performed using Student’s t-test, Mann-Whitney U test, Pearson’s correlation, and receiver operating characteristic (ROC) curve analysis in SPSS version 20.0.

Results

Among the 13 cytokines assessed, the levels of 3 cytokines (MIP-1α, IL-6, and IL-7) were negatively correlated with gestational age at delivery (P=0.028, P=0.002, and P=0.018, respectively). Sensitivities of MIP-1α, IL-6, and IL-17α were 70%, 80%, and 75%, respectively, and their specificities were 57%, 65%, and 69%, respectively. The sensitivity and specificity of fFN were 33% and 95%, respectively.

Conclusion

In symptomatic women diagnosed with PTL and/or pPROM, cytokines from cervicovaginal fluid, especially IL-6 and IL-17α, could be better predictive markers of PTB than fFN.

The Identification of Immune-Related Plasma Proteins Associated with Spontaneous Preterm Delivery and Intra-Amniotic Infection in Women with Premature Cervical Dilation or an Asymptomatic Short Cervix

BACKGROUND

We aimed to investigate whether various immune-related plasma proteins, alone or in combination with conventional clinical risk factors, can predict spontaneous preterm delivery (SPTD) and intra-amniotic infection in women with premature cervical dilation or a short cervix (≤ 25 mm).

METHODS

This retrospective study included 80 asymptomatic women with premature cervical dilation (n = 50) or a short cervix (n = 30), who underwent amniocentesis at 17-29 weeks. Amniotic fluid (AF) was cultured, and maternal plasma was assayed for interleukin (IL)-6, matrix metalloproteinase (MMP)-9, tissue inhibitor of metalloproteinases (TIMP)-1, and complements C3a and C5a, using enzyme-linked immunosorbent assay (ELISA) kits. The primary outcome measures were SPTD at < 32 weeks and positive AF cultures.

RESULTS

The plasma levels of IL-6, C3a, and C5a, but not of MMP-9 and TIMP-1, were significantly higher in women with SPTD at < 32 weeks than in those who delivered at ≥ 32 weeks. The women who delivered at < 32 weeks had more advanced cervical dilatation, and higher rates of antibiotic and tocolytic administration and were less likely to be given vaginal progesterone than those who delivered at ≥ 32 weeks. Using a stepwise regression analysis, a combined prediction model was developed, which included the plasma IL-6 and C3a levels, and cervical dilatation (area under the curve [AUC], 0.901). The AUC for this model was significantly greater than that for any single variable included in the predictive model. In the univariate analysis, plasma IL-6 level was the only significant predictor of intra-amniotic infection.

CONCLUSION

In women with premature cervical dilation or a short cervix, maternal plasma IL-6, C3a, and C5a levels could be useful non-invasive predictors of SPTD at < 32 weeks. A combination of these biomarkers and conventional clinical factors may clearly improve the predictability for SPTD, as compared with the biomarkers alone. An increased plasma level of IL-6 predicted intra-amniotic infection.

A Protein Microarray Analysis of Plasma Proteins for the Prediction of Spontaneous Preterm Delivery in Women with Preterm Labor

We aimed to identify novel biomarkers in maternal plasma that predict spontaneous preterm delivery (SPTD) in women with preterm labor (PTL) using an antibody microarray and to develop the best prediction model for SPTD based on these biomarkers in combination with clinical and ultrasound factors. This retrospective cohort study included 215 women with singleton pregnancies and PTL (23-33 weeks) who gave plasma samples. In a nested case-control study design, plasma proteomes from SPTD (case subjects, n = 15) and term delivery (control subjects, n = 15) groups were differentially profiled using a membrane-based antibody microarray. Six candidate biomarkers of interest were validated by enzyme-linked immunosorbent assay (ELISA) in the total cohort (n = 215). Cervical lengths were also measured. The primary outcome measure was SPTD within 48 h after sampling. Twenty of the molecules studied displayed significant intergroup differences. Validation by ELISA confirmed significantly higher levels of plasma endostatin and lipopolysaccharide binding protein (LBP) in women who had SPTD within 48 h than in those delivering after 48 h. However, plasma macrophage inflammatory protein (MIP)-1α levels were significantly lower in women who delivered within 48 h. A combined model was developed to predict SPTD within 48 h using a stepwise regression procedure, which included plasma endostatin and LBP levels, nulliparity, and cervical length (area under the curve = 0.920). Plasma LBP, endostatin, and MIP-1α are potential new biomarkers for predicting imminent SPTD and a combined noninvasive model based on these biomarkers and clinical and ultrasound factors can accurately predict imminent SPTD in women with PTL.

Antenatal and neonatal antecedents of learning limitations in 10-year old children born extremely preterm

BACKGROUND

Children born extremely preterm are at increased risk of learning limitations.

AIM

To identify the antecedents of learning limitations of children born extremely preterm.

STUDY DESIGN

Prospective observational study from birth to age 10 years. Variables entered into the multinomial logistic regression analyses were ordered temporally, with the earliest occurring predictors/covariates of each learning limitation risk entered first and not displaced by later occurring covariates.

SUBJECTS

874 children who were born before the 28th week of gestation.

OUTCOME MEASURES

A reading limitation was defined as a score one or more standard deviations below the expected mean on the WIAT-III Word Reading and a mathematics limitation was defined as a similarly low score on the Numerical Operations component.

RESULTS

56 children had a "reading ONLY" limitation, 132 children had a "math ONLY" limitation and 89 children had "reading AND math" limitations. All risk profiles included an indicator of socioeconomic disadvantage (e.g., mother's "racial" identity and eligibility for government-provided health care insurance), an indicator of newborn's immaturity/vulnerability (e.g., high illness severity score, receipt of hydrocortisone, and/or ventilator-dependence at 36 weeks post-menstruation), and all but the math only limitation included an indicator of fetal growth restriction and inflammation (i.e., pregnancy urinary tract infection or late ventilator-dependence).

CONCLUSIONS

The themes of socioeconomic disadvantage and immaturity/vulnerability characterize all three risk profiles, while the themes of fetal growth restriction and inflammation are characteristic of a reading limitation only, and the reading and math limitations entity.

Cervical cerclage placement decreases local levels of proinflammatory cytokines in patients with cervical insufficiency

BACKGROUND

Cervical insufficiency is characterized by premature, progressive dilation and shortening of the cervix during pregnancy. If left unattended, this can lead to the prolapse and rupture of the amniotic membrane, which usually results in midtrimester pregnancy loss or preterm birth. Previous studies have shown that proinflammatory cytokines such as interleukin-1β, interleukin-6, interleukin-8, and tumor necrosis factor alpha are up-regulated in normal parturition but are also associated with preterm birth. Studies evaluating such markers in patients with cervical insufficiency have evaluated only their diagnostic potential. Even fewer studies have studied them within the context of cerclage surgery.

OBJECTIVES(S)

The objective of the study was to evaluate the impact of local and systemic inflammatory markers on the pathogenesis of cervical insufficiency and the effect of cerclage surgery on the local immune microenvironment of women with cervical insufficiency.

STUDY DESIGN

We recruited 28 pregnant women (12-20 weeks' gestation) diagnosed with insufficiency and referred for cerclage surgery and 19 gestational age-matched normal pregnant women as controls. Serum and cervicovaginal fluid samples were collected before and after cerclage surgery and during a routine checkup for normal women and analyzed using a targeted 13-plex proinflammatory cytokine assay.

RESULTS

Before surgery, patients with cervical insufficiency had higher levels of interleukin-1β, interleukin-6, interleukin-12, monocyte chemoattractant protein-1 and tumor necrosis factor alpha in cervicovaginal fluid compared to controls, but after surgery, these differences disappeared. No differences were found in serum of insufficiency versus control women. In patients with insufficiency, the levels of interleukin-1β, interleukin-6, interleukin-8, monocyte chemoattractant protein-1, and interferon gamma in cervicovaginal fluid declined significantly after cerclage compared with before intervention, but these changes were not detected in serum.

CONCLUSION

Compared with normal women, patients with cervical insufficiency have elevated levels of proinflammatory cytokines in cervicovaginal fluid but not in serum, suggesting a dysregulation of the local immune environment. Cerclage intervention led to a significant decline in these proinflammatory cytokines, suggesting that cerclage may help reduce local inflammation in cervical insufficiency.

Non-invasive prediction of preterm birth in women with cervical insufficiency or an asymptomatic short cervix (≤25 mm) by measurement of biomarkers in the cervicovaginal fluid

OBJECTIVE

To determine whether various proteins in the cervicovaginal fluid (CVF) known to be involved in immune regulation, alone or in combination with clinical risk factors, can predict spontaneous preterm delivery (SPTD) in women with cervical insufficiency or a short cervix (≤25 mm).

METHODS

This retrospective cohort study included 62 asymptomatic women with cervical insufficiency (n = 27) or an asymptomatic short cervix (n = 35) at 18-27 weeks. CVF swab samples were taken for assays of vitamin D binding protein (VDBP), interleukin (IL)-8, matrix metalloproteinases (MMP)-9, tissue inhibitor of metalloproteinases (TIMP)-1, and Dickkopf-related protein 3 (DKK3) before cervical examination, and maternal blood was collected for the determination of the C-reactive protein (CRP) level. The primary outcome measurement was SPTD at <32 weeks of gestation. Logistic regression analysis and receiver operating characteristic curves were used for the statistical analyses.

RESULTS

The rate of SPTD at <32 weeks was 40.3% (25/62). The CVF levels of VDBP, TIMP-1, and DKK3, but not IL-8 and MMP-9, were significantly higher in the women who had SPTD at <32 weeks than in those who did not deliver spontaneously at <32 weeks. The women who had SPTD at <32 weeks had a significantly more advanced cervical dilatation at presentation and a higher level of serum CRP. Using the stepwise regression analysis, a prediction model was developed by combining various proteins in the CVF and clinical factors, resulting in the inclusion of cervical dilatation, CVF VDBP, and use of corticosteroids (area under curve, 0.909).

CONCLUSIONS

In women with cervical insufficiency or a short cervix, VDBP, TIMP-1, and DKK3 in the CVF may be useful as non-invasive predictors of SPTD at <32 weeks. A combination of these markers and clinical factors appears to improve the predictability of SPTD compared with the markers alone.