The preterm prediction study: granulocyte colony-stimulating factor and spontaneous preterm birth. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network

Absolute counts of leukocyte subsets in peripheral blood in pregnancies complicated by preterm prelabour rupture of membranes

BACKGROUND

This study aimed to assess variations in the absolute counts of various leukocyte subsets in the peripheral blood of women with pregnancies affected by preterm prelabour rupture of membranes (PPROM), in relation to the presence of intra-amniotic inflammation (IAI).

METHODS

The study included fifty-two women with singleton pregnancies experiencing PPROM. Absolute counts of different leukocyte subpopulations, such as granulocytes, monocytes, lymphocytes, T cells and their subsets, B cells and their subsets, and NK cells and their subsets, were measured in maternal peripheral blood samples using multicolour flow cytometry. IAI was identified by elevated concentrations of interleukin 6 (IL-6) in the amniotic fluid, which was collected through transabdominal amniocentesis.

RESULTS

Women with IAI exhibited higher absolute counts of leukocytes (p = 0.003), granulocytes (p = 0.008), and monocytes (p = 0.009). However, the presence of IAI did not significantly affect the absolute counts of lymphocytes or their subpopulations.

CONCLUSIONS

The study found that IAI is associated with changes in the absolute counts of leukocytes from the innate immunity compartment in the peripheral blood of women with pregnancies complicated by PPROM. Conversely, it does not significantly alter the counts of cells from the adaptive immune system. The changes observed may reflect the natural, temporal, and localised characteristics of IAI.

Cord blood cytokine profiles in children later diagnosed with autism spectrum disorder: Results from the prospective MARBLES study

In studies investigating the etiology and pathophysiology of autism spectrum disorder (ASD), immune dysregulation is commonly observed, with elevated levels of inflammatory cytokines frequently found in gestational tissues. However, studies investigating the relationship between early immune dysregulation within the umbilical cord blood (CB) compartment and neurodevelopmental outcomes remains limited. In this exploratory study, we utilized data from the prospective Markers for Autism Risk in Babies - Learning Early Signs (MARBLES) study to examine cytokine levels in the plasma fraction of CB in infants later diagnosed with ASD (n = 38) compared to infants typically developing (TD) at age 3 years (n = 103), using multiplex cytokine assays. Our findings reveal altered levels of several inflammatory cytokines in children later diagnosed with ASD, including increased granulocyte colony-stimulating factor (G-CSF) and decreased interleukin-1α (IL-1α), IL-1β, and IL-4 in CB. Furthermore, we identified several associations between behaviors and levels of cytokines, chemokines and growth factors. IL-1α, IL-17A, interferon γ-induced protein 10 (IP-10), and epidermal growth factor (EGF) were associated with worse scores on Autism Diagnostic Observation Schedule (ADOS) and the Mullen Scales of Early Learning (MSEL) assessments. In summary, our study demonstrates dysregulated levels of inflammatory cytokine mediators in the CB of children later diagnosed with ASD and that inflammatory mediators were associated with ASD severity, comorbid behaviors, and neurodevelopmental measures. These findings have important implications for the possible predictive value of early cytokine measures in neurodevelopmental outcomes and subsequent behavioral manifestations.

The Association of Vitamin D during Pregnancy and mRNA Expression Levels of Inflammatory Factors with Preterm Birth and Prelabor Rupture of Membranes

The aim of this study was to elucidate the association between vitamin D (VD) and the risk for preterm birth (PTB) and prelabor rupture of membranes (PROM). This study included two parts, with a cohort study and a case-control study. Plasma 25-hydroxyvitamin vitamin D [25(OH)D] levels in three trimesters in the cohort study and maternal 25(OH)D before delivery in the case-control study were measured. Quantitative real-time PCR was used to detect relative mRNA expression levels of the inflammatory factors associated with pyroptosis in peripheral blood mononuclear cell (PBMC), placenta and fetal membranes. Multinomial logistic regression and the Wilcoxon test were applied to analyze the associations. In the cohort study, 6381 pregnant women were included. We found that VD deficiency in T3 (PTB without PROM: OR = 1.90, 95% CI: 1.02-3.55, Term PROM (TPROM): OR = 0.76, 95% CI: 0.59-0.98) and less change of 25(OH)D between T1 and T3 (PTB without PROM: OR = 2.32, 95% CI: 1.07-5.06, TPROM: OR = 0.73, 95% CI: 0.56-0.96) were associated with the increased risk of PTB without PROM, while there was a decreased risk of TPROM. Neither VD, nor the increase of VD during pregnancy was associated with the premature rupture of membranes preterm delivery (PPROM). In the case-control study, there were no associations between VD during delivery and PTB or PROM (TPROM: OR = 1.33, 95% CI: 0.52-3.44); PTB without PROM: OR = 1.66, 95% CI: 0.33-8.19; PPROM: OR = 1.19, 95% CI: 0.42-3.40). The mRNA expression of NLRP1 (NOD-like receptor thermal protein domain associated protein 1) (p = 0.0165) in PBMC in the TPROM group was higher than that in the term group, and IL-18 (p = 0.0064) was lower than that in the term group. Plasma 25(OH)D in T3 and the increase of 25(OH)D between T1 and T3 were associated with a lower risk for PTB without PROM but a higher risk for TPROM. Further studies are warranted to clarify the association between VD and PTB and PROM and its mechanism.

Roles of the Microbiota of the Female Reproductive Tract in Gynecological and Reproductive Health

The microbiome of the female reproductive tract defies the convention that high biodiversity is a hallmark of an optimal ecosystem. Although not universally true, a homogeneous vaginal microbiome composed of species of Lactobacillus is generally associated with health, whereas vaginal microbiomes consisting of other taxa are generally associated with dysbiosis and a higher risk of disease. The past decade has seen a rapid advancement in our understanding of these unique biosystems. Of particular interest, substantial effort has been devoted to deciphering how members of the microbiome of the female reproductive tract impact pregnancy, with a focus on adverse outcomes, including but not limited to preterm birth. Herein, we review recent research efforts that are revealing the mechanisms by which these microorganisms of the female reproductive tract influence gynecologic and reproductive health of the female reproductive tract.

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.

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.

Is there a maternal blood biomarker that can predict spontaneous preterm birth prior to labour onset? A systematic review

INTRODUCTION

The ability to predict spontaneous preterm birth (sPTB) prior to labour onset is a challenge, and it is currently unclear which biomarker(s), may be potentially predictive of sPTB, and whether their predictive power has any utility. A systematic review was conducted to identify maternal blood biomarkers of sPTB.

METHODS

This study was conducted according to PRISMA protocol for systematic reviews. Four databases (MEDLINE, EMBASE, CINAHL, Scopus) were searched up to September 2021 using search terms: "preterm labor", "biomarker" and "blood OR serum OR plasma". Studies assessing blood biomarkers prior to labour onset against the outcome sPTB were eligible for inclusion. Risk of bias was assessed based on the Newcastle Ottawa scale. Increased odds of sPTB associated with maternal blood biomarkers, as reported by odds ratios (OR), or predictive scores were synthesized. This review was not prospectively registered.

RESULTS

Seventy-seven primary research articles met the inclusion criteria, reporting 278 unique markers significantly associated with and/or predictive of sPTB in at least one study. The most frequently investigated biomarkers were those measured during maternal serum screen tests for aneuploidy, or inflammatory cytokines, though no single biomarker was clearly predictive of sPTB based on the synthesized evidence. Immune and signaling pathways were enriched within the set of biomarkers and both at the level of protein and gene expression.

CONCLUSION

There is currently no known predictive biomarker for sPTB. Inflammatory and immune biomarkers show promise, but positive reporting bias limits the utility of results. The biomarkers identified may be more predictive in multi-marker models instead of as single predictors. Omics-style studies provide promising avenues for the identification of novel (and multiple) biomarkers. This will require larger studies with adequate power, with consideration of gestational age and the heterogeneity of sPTB to identify a set of biomarkers predictive of sPTB.

Second trimester fetal thymus size in association to preterm birth

OBJECTIVES

The aim of this study was to compare the second trimester thymus-thorax-ratio (TTR) between fetuses born preterm (study group) and those born after 37 weeks of gestation were completed (control group).

METHODS

This study was conducted as a retrospective evaluation of the ultrasound images of 492 fetuses in the three vessel view. The TTR was defined as the quotient of a.p. thymus diameter and a.p. thoracic diameter.

RESULTS

Fetuses that were preterm showed larger TTR (p<0.001) the second trimester than those born after 37 weeks of gestation were completed. The sensitivity of a binary classifier based on TTR for predicting preterm birth (PTB) was 0.792 and the specificity 0.552.

CONCLUSIONS

In our study, fetuses affected by PTB showed enlarged thymus size. These findings led us to hypothesize, that inflammation and immunomodulatory processes are altered early in pregnancies affected by PTB. However, TTR alone is not able to predict PTB.

Review: Ischemia Reperfusion Injury-A Translational Perspective in Organ Transplantation

Thanks to the development of new, more potent and selective immunosuppressive drugs together with advances in surgical techniques, organ transplantation has emerged from an experimental surgery over fifty years ago to being the treatment of choice for many end-stage organ diseases, with over 139,000 organ transplants performed worldwide in 2019. Inherent to the transplantation procedure is the fact that the donor organ is subjected to blood flow cessation and ischemia during harvesting, which is followed by preservation and reperfusion of the organ once transplanted into the recipient. Consequently, ischemia/reperfusion induces a significant injury to the graft with activation of the immune response in the recipient and deleterious effect on the graft. The purpose of this review is to discuss and shed new light on the pathways involved in ischemia/reperfusion injury (IRI) that act at different stages during the donation process, surgery, and immediate post-transplant period. Here, we present strategies that combine various treatments targeted at different mechanistic pathways during several time points to prevent graft loss secondary to the inflammation caused by IRI.

Maternal blood biomarkers and adverse pregnancy outcomes: a systematic review and meta-analysis

Background: Pregnancy is a vulnerable period for the mother and the infant and exposures to environmental chemicals in utero can influence neonatal morbidity and mortality. There is a momentum toward understanding and exploring the current maternal biological mechanisms specific to in utero effects, to improve birth outcomes. This study aims to examine the current understanding of the role of biomarkers that may be associated with term of pregnancy, infant birth weights and infant development in utero.Methods: Electronic searches were conducted in PubMed, Embase, OvidMD, and Scopus databases; and all relevant research articles in English were retrieved. Studies were selected if they evaluated maternal blood plasma/serum biomarkers proposed to influence adverse birth outcomes in the neonate. Data were extracted on characteristics, quality, and odds ratios from each study and meta-analysis was conducted.Results: A total of 54 studies (35 for meta-analysis), including 43,702 women, 50 plasma markers and six descriptors of birth outcomes were included in the present study. The random effect point estimates for risk of adverse birth outcomes were 1.61(95%CI: 1.39-1.85, p < 0.0001) for inflammation-related biomarkers and 1.65(95%CI: 1.22-2.25, p = 0.0013) for growth factor/hormone-related biomarkers. All subgroups of plasma markers showed significant associations with adverse birth outcomes with no apparent study bias.Conclusions: The two subsets of plasma markers identified in this study (inflammation-related and growth factor/hormone-related) may serve as potentially valuable tools in the investigation of maternal molecular mechanisms, especially select pathways underlying inflammatory and immunological mediation in terms of modulating adverse infant outcomes. Future large, prospective cohort studies are needed to validate the promising plasma biomarkers, and to examine other maternal biological matrices such as cervicovaginal fluid and urine.

Inflammation-mediated fetal injury by maternal granulocyte-colony stimulating factor and high-dose intraamniotic endotoxin in the caprine model

Objective:

To define a novel experimental model with maternal intravenous (i.v.) granulocyte-colony stimulating factor (G-CSF) followed by a single- and high-dose of 20 mg intra-amniotic (IA) endotoxin to induce fetal brain injury in the preterm fetal goat.

Materials and Methods:

Pregnant goats (n=4) were given 50 microg/day G-CSF into the maternal jugular vein through gestational days 110-115 (term, 150 days). At gestational day 115, 20 mg of IA endotoxin was administered. Following preterm delivery at day 120 by cesarean section umbilical cord, fetal lung and brain tissues were harvested for histopathology, immunohistochemistry, and electron microscopy. Inflammatory markers were evaluated in the amniotic fluid and fetal plasma.

Results:

Necrotizing funisitis with abundant leukocyte infiltration and fetal brain injury was induced in all the fetuses in the experimental group.

Conclusion:

Maternal i.v. G-CSF for 5 days followed by 20 mg of IA endotoxin is a feasible caprine model to exacerbate intrauterine inflammation.

The common vaginal commensal bacterium Ureaplasma parvum is associated with chorioamnionitis in extreme preterm labor

OBJECTIVE

To assess the association of vaginal commensal and low-grade pathogenic bacteria including Ureaplasma parvum, Ureaplasma urealyticum, Mycoplasma hominis, Mycoplasma genitalium, Group B streptococcus (GBS), and Gardnerella vaginalis, in women who delivered preterm at less than 37-week gestation in the presence or absence of inflammation of the chorioamnionitic membranes.

METHODS

A case control study involving women who delivered before 37-week gestation with and without inflammation of chorioamnionitic membranes. A total of 57 placental samples were histologically examined for polymorphonuclear leukocyte infiltration of placental tissue for evidence of chorioamnionitis, and by type-specific nucleic acid amplification for evidence of infection with one or more of the target bacteria. Demographic data were collected for each mother.

RESULTS

Among the 57 placental samples, 42.1% had chorioamnionitis and 24.6% delivered in the second trimester of pregnancy; U. parvum, U. urealyticum, G. vaginalis, and GBS were all detected in the study with respective prevalence of 19.3%, 3.5%, 17.5%, and 15.8%; M. genitalium and M. hominis were not detected. U. parvum was significantly associated with chorioamnionitis (p = 0.02; OR 5.0; (95% CI 1.2-21.5) and was more common in women who delivered in the second (35.7%) compared to the third trimester of pregnancy (13.9%). None of the other bacteria were associated with chorioamnionitis or earlier delivery, and all G. vaginalis-positive women delivered in the third trimester of pregnancy (p = 0.04).

CONCLUSIONS

The detection of U. parvum in placental tissue was significantly associated with acute chorioamnionitis in women presenting in extreme preterm labor.

Identifying metabolite markers for preterm birth in cervicovaginal fluid by magnetic resonance spectroscopy

INTRODUCTION

Preterm birth (PTB) may be preceded by changes in the vaginal microflora and metabolite profiles.

OBJECTIVES

We sought to characterise the metabolite profile of cervicovaginal fluid (CVF) of pregnant women by 1H NMR spectroscopy, and assess their predictive value for PTB.

METHODS

A pair of high-vaginal swabs was obtained from pregnant women with no evidence of clinical infection and grouped as follows: asymptomatic low risk (ALR) women with no previous history of PTB, assessed at 20-22 gestational weeks, g.w., n = 83; asymptomatic high risk (AHR) women with a previous history of PTB, assessed at both 20-22 g.w., n = 71, and 26-28 g.w., n = 58; and women presenting with symptoms of preterm labor (PTL) (SYM), assessed at 24-36 g.w., n = 65. Vaginal secretions were dissolved in phosphate buffered saline and scanned with a 9.4 T NMR spectrometer.

RESULTS

Six metabolites (lactate, alanine, acetate, glutamine/glutamate, succinate and glucose) were analysed. In all study cohorts vaginal pH correlated with lactate integral (r = -0.62, p < 0.0001). Lactate integrals were higher in the term ALR compared to the AHR (20-22 g.w.) women (p = 0.003). Acetate integrals were higher in the preterm versus term women for the AHR (20-22 g.w.) (p = 0.048) and SYM (p = 0.003) groups; and was predictive of PTB < 37 g.w. (AUC 0.78; 95 % CI 0.61-0.95), and delivery within 2 weeks of the index assessment (AUC 0.84; 95 % CI 0.64-1) in the SYM women, whilst other metabolites were not.

CONCLUSION

High CVF acetate integral of women with symptoms of PTL appears predictive of preterm delivery, as well as delivery within 2 weeks of presentation.

Placental Infection With Ureaplasma species Is Associated With Histologic Chorioamnionitis and Adverse Outcomes in Moderately Preterm and Late-Preterm Infants

OBJECTIVE

The human Ureaplasma species are the microbes most frequently isolated from placentae of women who deliver preterm. The role of Ureaplasma species has been investigated in pregnancies at <32 weeks of gestation, but currently no studies have determined the prevalence of ureaplasmas in moderately preterm and late-preterm (hereafter, "moderate/late preterm") infants, the largest cohort of preterm infants.

METHODS

Women delivering moderate/late preterm infants (n = 477) and their infants/placentae (n = 535) were recruited, and swab specimens of chorioamnion tissue, chorioamnion tissue specimens, and cord blood specimens were obtained at delivery. Swab and tissue specimens were cultured and analyzed by 16S ribosomal RNA polymerase chain reaction (PCR) for the presence of microorganisms, while cord blood specimens were analyzed for the presence of cytokines, chemokines, and growth factors.

RESULTS

We detected microorganisms in 10.6% of 535 placentae (443 were delivered late preterm and 92 were delivered at term). Significantly, Ureaplasma species were the most prevalent microorganisms, and their presence alone was associated with histologically confirmed chorioamnionitis in moderate/late preterm and term placentae (P < .001). The presence of ureaplasmas in the chorioamnion was also associated with elevated levels of granulocyte colony-stimulating factor (P = .02).

CONCLUSIONS

These findings have important implications for infection and adverse pregnancy outcomes throughout gestation and should be of major consideration for obstetricians and neonatologists.

Comparison of serum granulocyte colony-stimulating factor levels between preterm and term births

OBJECTIVE

Preterm birth (PTB) is the major obstetric problem in developed countries, accounting for the majority of neonatal mortality and morbidity. Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic cytokine that mediates the increase in leukocytes in pregnancy and may play a role in placentation. We aimed to investigate the differences of serum G-CSF levels between subsequent spontaneous PTB and term-delivered healthy pregnant women.

MATERIAL AND METHODS

Serum samples, collected from total of 600 singleton otherwise healthy pregnants at 24-28 weeks of gestation during a routine antenatal visit, were used to assess G-CSF levels; 40 of the total pregnants who delivered their infants spontaneously after preterm labor before 37 weeks of gestation were selected as the study group. Also, 120 pregnants were selected as a control group using a 1/3 ratio. Student's t-test, chi-square test, Mann-Whitney U-tests, and ROC curve analysis for prediction of PTB were used for the comparison of groups. P<0.05 was accepted as statistically significant.

RESULTS

There was no significant difference in maternal serum G-CSF levels between the study and control groups (p=0.28) but maternal white blood cell (WBC) count was significantly different between them (p=0.00). In addition, G-CSF was insufficient in the prediction of PTB (AUC=0.419). In the preterm and term groups, no correlation was found between WBC and G-CSF (p=0.165 vs. p=0.703).

CONCLUSION

There were no differences in serum levels of G-CSF between term- and preterm-delivered pregnants. There was no predictive role for serum G-CSF in PTB.

Can preterm labour be predicted in low risk pregnancies? Role of clinical, sonographic, and biochemical markers

Background and Objectives. This is a prospective nested cohort study conducted over a period of 3 years. 2644 women were recruited, out of which final analysis was done for 1884 women. Methods. Cervicovaginal and blood samples were collected for all recruited women. Out of these, 137 women who delivered before 35 weeks were treated as cases and equal number of matched controls were chosen. Analysis of samples for serum G-CSF, AFP, ferritin, and cervicovaginal interleukin-6 and IGFBP-1 was done. Results. Poor orodental hygiene, which can be a social marker, was significantly more common in women who delivered preterm (P = 0.008). Serum alkaline phosphatase and serum ferritin were found to be significantly associated with preterm deliveries. The 90th percentile value of these parameters was considered as cut-off as there is no specific cut-off. Conclusions. Our study did not prove usefulness of any predictive marker. Serum ferritin and alkaline phosphatase were found to have correlation but their values are affected in many conditions and need to be elucidated with caution. Larger studies are needed for predicting preterm labour in asymptomatic women.

Proteomic analysis of cervical vaginal fluid proteins among women in recurrent preterm labor

OBJECTIVE

Proteomic analysis of four cervical-vaginal fluid (CVF) proteins to identify biomarkers of recurrent preterm birth (rPTB) in at-risk women prior to onset of preterm labor.

METHODS

Nested case control study from 2007 to 2011 of women with prior spontaneous preterm birth(s) (PTB) who underwent serial CVF sampling. Mass spectrometry analysis was used and ELISA analysis was performed to validate candidates.

RESULTS

108 patients were enrolled and 10 cases and 20 gestational age matched controls were analyzed after exclusions. Of 748 CVF proteins identified, 72 had statistically significant (p < 0.05) expression differences and 38 were highly differentially expressed (p < 0.01). Four candidate proteins were abundant and involved in immune/inflammatory response, but ELISA analysis did not confirm altered expression patterns.

CONCLUSION

The lack of confirmation of potential biomarkers identified by mass spectrometry and ELISA demonstrates the challenges of validating PTB biomarkers and suggests that a panel of biomarkers would improve the predictive value of CVF testing.

Cervical mucus properties stratify risk for preterm birth

BACKGROUND

Ascending infection from the colonized vagina to the normally sterile intrauterine cavity is a well-documented cause of preterm birth. The primary physical barrier to microbial ascension is the cervical canal, which is filled with a dense and protective mucus plug. Despite its central role in separating the vaginal from the intrauterine tract, the barrier properties of cervical mucus have not been studied in preterm birth.

METHODS AND FINDINGS

To study the protective function of the cervical mucus in preterm birth we performed a pilot case-control study to measure the viscoelasticity and permeability properties of mucus obtained from pregnant women at high-risk and low-risk for preterm birth. Using extensional and shear rheology we found that cervical mucus from women at high-risk for preterm birth was more extensible and forms significantly weaker gels compared to cervical mucus from women at low-risk of preterm birth. Moreover, permeability measurements using fluorescent microbeads show that high-risk mucus was more permeable compared with low-risk mucus.

CONCLUSIONS

Our findings suggest that critical biophysical barrier properties of cervical mucus in women at high-risk for preterm birth are compromised compared to women with healthy pregnancy. We hypothesize that impaired barrier properties of cervical mucus could contribute to increased rates of intrauterine infection seen in women with preterm birth. We furthermore suggest that a robust association of spinnbarkeit and preterm birth could be an effectively exploited biomarker for preterm birth prediction.

Is thrombin activation predictive of subsequent preterm delivery?

OBJECTIVE

To determine the relation between thrombin generation (measured by thrombin-antithrombin [TAT] complexes) early in pregnancy and subsequent preterm delivery.

STUDY DESIGN

Select cohort of 731 women undergoing indicated second trimester amniocentesis prospectively followed to delivery. Primary outcome was preterm delivery. TAT levels were examined continuously and categorized by quartiles. Multivariable techniques were applied to adjust for potential confounders. Receiver operating characteristic curve analysis was used to determine a discriminatory cutoff level for TAT complexes.

RESULTS

TAT concentration was significantly higher in women who delivered preterm (median, 98.9 mcg/L) than in those who did not (median, 66.3 mcg/L; P < .001). This difference persisted when 55 spontaneous preterm deliveries (median, 87.6 mcg/L) and 34 indicated preterm deliveries (median, 117.7 mcg/L) were separately compared with controls (P = .04 and P < .001, respectively). Crude and adjusted odds ratio for preterm delivery in the upper 2 TAT quartiles relative to the uppermost quartile relative to the lowest quartile were 2.45 (95% confidence interval [CI], 1.36-4.72; P = .004) and 2.31 (95% CI, 1.18-4.65; P = .017), respectively. Despite these distinct differences, the area under the receiver operating characteristic curve was only 0.62 (95% CI, 0.56-0.69), indicating poor performance of TAT concentration as a risk discriminator.

CONCLUSION

Amniotic fluid levels of TAT complexes in the second trimester are elevated in women who subsequently deliver preterm, suggesting that thrombin generation may be involved in the various etiopathogenic mechanisms leading to preterm delivery.

Relationship between the neonatal white blood cell count and histologic chorioamnionitis in preterm newborns

OBJECTIVE

The aim was to examine the relationship between neonatal white blood cell (WBC) count and the diagnosis of histologic chorioamnionitis (HCA).

DESIGN

We measured WBC, a widely used marker of inflammation, to evaluate whether the values at birth were associated with HCA.

SETTING

NICU, Department of Pediatrics of Padua University, Padua, Italy.

SUBJECTS

WBC count was evaluated in 71 preterm neonates (<32 weeks of gestation) with HCA and in a control group without HCA on day 1, 3, and 6 after delivery. Logistic regression analysis and diagnostic accuracy analysis were used to assess the association between WBC counts and HCA.

MAIN RESULTS

WBC levels were significantly higher in infants with HCA than in those without HCA (Median IQR, WBC (x10(9)/l): day 1, 13.2 (6.2-21.8) vs 8.1 (6-11.4), p < 0.001; day 3, 17.4 (11.4-26.9) vs 6.3 (5.2-8.3), p < 0.001; day 6, 18.4 (11.1-31) vs 6.5 (4.4-9), p < 0.0001). The neonatal WBC count on the third day of life was the most sensitive parameter associated with HCA (sensitivity: 0.80; specificity: 0.88). The cut-off value based on the ROC curve was 10 (x10(9)/l).

CONCLUSIONS

WBC count in the third day of life is strongly associated with HCA.

Midtrimester amniotic fluid concentrations of interleukin-6 and interferon-gamma-inducible protein-10: evidence for heterogeneity of intra-amniotic inflammation and associations with spontaneous early (<32 weeks) and late (>32 weeks) preterm delivery

INTRODUCTION

Intra-amniotic inflammation is traditionally defined as an elevation of amniotic fluid interleukin (IL)-6. Previous case control studies have suggested an association between an elevated midtrimester amniotic fluid IL-6 and preterm delivery, although such an association has been recently challenged. Intra-amniotic inflammation can also be defined by an elevation of the T-cell chemokine, Interferon-gamma-inducible protein (IP)-10. An elevation in amniotic fluid IP-10 has been associated with chronic chorioamnionitis, a lesion frequently found in late spontaneous preterm birth and fetal death. In contrast, an elevation in amniotic fluid IL-6 is typically associated with acute chorioamnionitis and funisitis. This study was conducted to examine the relationship between an elevation in amniotic fluid IL-6 in the midtrimester and preterm delivery at or before 32 weeks of gestation, and the amniotic fluid concentration of IP-10 and preterm delivery after 32 weeks of gestation.

MATERIALS AND METHODS

This cohort study included 847 consecutive women undergoing genetic midtrimester amniocentesis; in 796 cases, amniotic fluid and pregnancy outcome was available for study after exclusion of abnormal karyotype and/or fetal congenital anomalies. Spontaneous preterm delivery was defined as early (≤32 weeks) or late (after 32 completed weeks of pregnancy). The amniotic fluid and maternal blood concentrations of IL-6 and IP-10 were measured by specific immunoassays.

RESULTS

1) The prevalence of preterm delivery was 8.3% (66/796), while those of early and late spontaneous preterm delivery were 1.5% (n=12), and 4.5% (n=36), respectively; 2) patients who had a spontaneous preterm delivery after 32 weeks of gestation had a higher median amniotic fluid IP-10 concentration than those who delivered at term [median 713 pg/mL, inter-quartile range (IQR) 509-1427 pg/mL vs. median 589 pg/mL, IQR 402-953 pg/mL; P=0.006] and an elevation of amniotic fluid IP-10 concentration above 502 pg/mL (derived from an ROC curve) was associated with late spontaneous preterm delivery [odds ratio 3.9 (95% CI 1.6-9.9)]; 3) patients who had a spontaneous preterm delivery ≤32 weeks of gestation had a higher median amniotic fluid IL-6 concentration than those who delivered at term [median 2052 pg/mL, IQR 435-3015 pg/mL vs. median 414 pg/mL, IQR 209-930 pg/mL; P=0.006], and an elevated amniotic fluid IL-6 concentration above 1740 pg/mL (derived from an ROC curve) was associated with early spontaneous preterm delivery [odds ratio 9.5 (95% CI 2.9-31.1)]; 4) subclinical intra-amniotic inflammation, defined as an elevation of IL-6 (≥2.9 ng/mL) or IP-10 (≥2.2 ng/mL) concentration above the 95th percentile of patients who had uncomplicated term delivery (n=652 for IL-6 and n=633 for IP-10), was observed in 6.3% (50/796) and 5.8% (45/770) of cases, respectively. Although each type of inflammation is a risk factor for spontaneous preterm delivery, many patients had a term delivery without complication; 5) the amniotic fluid in the midtrimester did not contain microorganisms detectable with cultivation techniques.

CONCLUSIONS

INTRA-amniotic inflammation is heterogeneous. Some patients have elevated amniotic fluid concentrations of IL-6, and are at risk for spontaneous preterm delivery before 32 weeks of gestation, while others have an elevated IP-10 (a chemotactic T-cell chemokine) and such patients are at risk for spontaneous preterm delivery after 32 weeks of gestation. A fraction of patients have subclinical intra-amniotic inflammation and deliver at term. The clinical significance of this condition remains to be determined.

[The role of infection in preterm birth]

Intrauterine infection could be responsible for 25% up to 40% of preterm births. This relationship was initially demonstrated using animal models, inducing their abortion by injecting bacteria or endotoxins. In human research, examination of amniocentesis fluid showed the anteriority of infection over labor induction, and the existence of a subclinical latency phase between these two phenomena. The ascending route is preponderant, and four stages can be distinguished: cervical and vaginal infection, chorio-decidual infection, intra-amniotic infection, fetal infection. The intrauterine infection is very frequent in case of early preterm birth (<30 WG). It is associated with an increase of neurological and pulmonary morbidity. Most commonly found bacterial species are mycoplasma species, but also Escherichia coli, Gardnerella vaginalis and streptococcus B. Several markers of the infection have been studied: a maternal leukocytosis>15,000/mm(3) or a C-Reactive Protein (CRP)>20mg/l, an increase of fibronectin and/or IL-6 cervical, a short cervical length especially before 32 WG, a leukocytosis of the amniotic fluid, and/or high interleukin concentrations. The main marker used for the newborn is the CRP, but other markers can also be used for an early diagnosis of an infection, especially interleukin 6.

Host factors that influence mother-to-child transmission of HIV-1: genetics, coinfections, behavior and nutrition

Mother-to-child transmission (MTCT) is the most important mode of HIV-1 acquisition among infants and children and it can occur in utero, intrapartum and postnatally through breastfeeding. Great progress has been made in preventing MTCT through use of antiretroviral regimens during gestation, labor/delivery and breastfeeding. The mechanisms of MTCT, however, are multifactorial and remain incompletely understood. This review focuses on select host factors affecting MTCT, in particular genetic factors, coexisting infections, behavioral factors and nutrition. Whereas much emphasis has been placed on decreasing maternal HIV-1 viral load, an important determinant of MTCT, through use of antiretroviral agents, complementary focus on overall maternal health is often neglected. By addressing coinfections in mothers and infants, improving the mother's nutritional status and modifying risky behaviors and practices, not only is maternal and child health improved, but a direct benefit in reducing MTCT can be derived. The study of genetic variations in susceptibility to HIV-1 infection is rapidly evolving, and the future is likely to bring revolutionary changes in HIV-1 prevention by enhancing natural resistance to infection and by individually tailoring pharmacologic regimens.

The role of granulocyte colony-stimulating factor in the neutrophilia observed in the fetal inflammatory response syndrome

OBJECTIVES

Fetal neutrophilia is present in two-thirds of cases with the fetal inflammatory response syndrome (FIRS). The mechanisms responsible for this finding have not been elucidated. Granulocyte colony-stimulating factor (G-CSF) is the primary physiologic regulator of neutrophil production and plays a key role in the rapid generation and release of neutrophils in stressful conditions (i.e., infection). The objective of this study was to determine: 1) whether FIRS was associated with changes in fetal plasma G-CSF concentrations; and 2) if fetal plasma G-CSF concentrations correlated with fetal neutrophil counts, chorioamnionitis, neonatal morbidity/mortality and cordocentesis-to-delivery interval.

STUDY DESIGN

Percutaneous umbilical cord blood sampling was performed in a population of patients with preterm labor (n=107). A fetal plasma interleukin-6 (IL-6) concentration >11 pg/mL was used to define FIRS. Cord blood G-CSF was measured by a sensitive and specific immunoassay. An absolute neutrophil count was determined and corrected for gestational age. Receiver operating characteristic (ROC) curve, survival analysis and Cox proportional hazard model were employed.

RESULTS

1) G-CSF was detected in all fetal blood samples; 2) fetuses with FIRS had a higher median fetal plasma G-CSF concentration than those without FIRS (P<0.001); 3) a fetal plasma G-CSF concentration ≥134 pg/mL (derived from an ROC curve) was associated with a shorter cordocentesis-to-delivery interval, a higher frequency of chorioamnionitis (clinical and histological), intra-amniotic infection, and composite neonatal morbidity/mortality than a fetal plasma concentration below this cut-off; and 4) a fetal plasma G-CSF concentration ≥134 pg/mL was associated with a shorter cordocentesis-to-delivery interval (hazard ratio 3.2; 95% confidence interval 1.8-5.8) after adjusting for confounders.

CONCLUSIONS

1) G-CSF concentrations are higher in the peripheral blood of fetuses with FIRS than in fetuses without FIRS; and 2) a subset of fetuses with FIRS with elevated fetal plasma G-CSF concentrations are associated with neutrophilia, a shorter procedure-to-delivery interval, chorio-amnionitis and increased perinatal morbidity and mortality.

Novel biomarkers for the prediction of the spontaneous preterm birth phenotype: a systematic review and meta-analysis

BACKGROUND

Being able to predict preterm birth is important, as it may allow a high-risk population to be selected for future interventional studies and help in understanding the pathways that lead to preterm birth.

OBJECTIVE

To investigate the accuracy of novel biomarkers to predict spontaneous preterm birth in women with singleton pregnancies and no symptoms of preterm labour.

SEARCH STRATEGY

Electronic searches in PubMed, Embase, Cinahl, Lilacs, and Medion, references of retrieved articles, and conference proceedings. No language restrictions were applied.

SELECTION CRITERIA

Observational studies that evaluated the accuracy of biomarkers proposed in the last decade to predict spontaneous preterm birth in asymptomatic women. We excluded studies in which biomarkers were evaluated in women with preterm labour.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data on study characteristics, quality, and accuracy. Data were arranged in 2 × 2 contingency tables and synthesised separately for spontaneous preterm birth before 32, 34, and 37 weeks of gestation. We used bivariate meta-analysis to estimate pooled sensitivities and specificities, and calculated likelihood ratios (LRs).

MAIN RESULTS

A total of 72 studies, including 89,786 women and evaluating 30 novel biomarkers, met the inclusion criteria. Only three biomarkers (proteome profile and prolactin in cervicovaginal fluid, and matrix metalloproteinase-8 in amniotic fluid) had positive LRs > 10. However, each of these biomarkers was evaluated in only one small study. Four biomarkers had a moderate predictive accuracy (interleukin-6 and angiogenin, in amniotic fluid; human chorionic gonadotrophin and phosphorylated insulin-like growth factor binding protein-1, in cervicovaginal fluid). The remaining biomarkers had low predictive accuracies.

CONCLUSIONS

None of the biomarkers evaluated in this review meet the criteria to be considered a clinically useful test to predict spontaneous preterm birth. Further large, prospective cohort studies are needed to evaluate promising biomarkers such as a proteome profile in cervicovaginal fluid.

Peripheral blood cytokine profiling during pregnancy and post-partum periods

PROBLEM

Pregnancy requires that the maternal immune system adapt to prevent rejection of the fetal semi-allograft. This immunologic adaptation may contribute to pregnancy-related alterations in disease susceptibility and severity of infections from viral pathogens such as influenza virus.

METHOD OF STUDY

As part of a larger study investigating the maternal systemic immune response during pregnancy, peripheral blood was collected three times during pregnancy and twice post-partum to measure serum levels of 23 cytokines, chemokines, and growth factors. This longitudinal study design allowed each woman's post-partum blood draw to serve as her own comparison, thus controlling for interpersonal variability in expression levels.

RESULTS

When compared to the post-partum samples, significant pregnancy-related changes in IFNγ, TNFα, VEGF, GCSF, Eotaxin, and MCP-1 expression were observed. These changes have significant immunologic effects in vivo and in culture.

CONCLUSION

Pregnancy-associated changes to steady state serum cytokines may have important immunologic consequence.

Integrated review of cytokines in maternal, cord, and newborn blood: part I--associations with preterm birth

Preterm birth (PTB; spontaneous delivery prior to 37 weeks gestation) affects one out of eight infants born in the United States and is the most common cause of neonatal morbidity and mortality. Although the pathogenesis of PTB is multifactorial, a growing body of literature supports the hypothesis that one cause of PTB is inflammation in pregnancy. Investigators have implicated mediators of inflammation, most notably proinflammatory cytokines, as being associated with and perhaps a playing a causal role in the pathogenesis of preterm labor and adverse early fetal outcomes. Though researchers have pursued the association of cytokines with preterm labor and subsequent early adverse fetal outcomes as a line of research, there has been little integration of diverse findings across studies. This systematic review appraises the empirical evidence from human studies for the association of levels of cytokines in blood with preterm labor and adverse early fetal outcome to examine the current state of the science in this important area of biobehavioral research. The most consistent finding is that increased levels of proinflammatory cytokines, particularly interleukin (IL) 6, IL-beta1, and tumor necrosis factor alpha (TNF-alpha), are associated with PTB as compared to levels found at term birth. However, there have been relatively few studies and results have not been consistent. Therefore, further research is needed to elucidate the association of these inflammatory mediators with adverse pregnancy outcomes.

Maternal serum granulocyte colony-stimulating factor levels and spontaneous preterm birth

OBJECTIVE

Preterm birth (PTB) remains a cause of substantial morbidity with an elusive etiology. Previous studies suggested an association of PTB with elevated serum levels of granulocyte colony-stimulating factor (G-CSF) at 28 weeks gestation. G-CSF, a hematopoietic cytokine, mediates the increase in leukocytes in pregnancy and may play a role in placentation. We evaluated the association between maternal serum G-CSF in the first and second trimesters and PTB.

METHODS

Serum samples collected for the Collaborative Perinatal Project (CPP) from women with normal pregnancy (n = 394) and PTB (n = 31), defined as delivery before 37 weeks gestation, were used to assess G-CSF levels. Linear regression was used to evaluate the relation of G-CSF with gestational age (GA) at birth. Logistic regression, conditional on GA at sample provision, was used to model the association between G-CSF and PTB.

RESULTS

G-CSF was significantly associated with gestational age at birth (p = 0.02). In conditional logistic regression models, G-CSF was significantly associated with PTB, with an adjusted odds ratio (AOR) of 1.52 (95% confidence interval [CI] 1.07, 2.16) per standard deviation (SD) increase.

CONCLUSIONS

Acute effects of G-CSF on PTB have been suggested. In our study we observed an association of higher serum G-CSF levels early in the second trimester with PTB, suggesting PTB as the culmination process beginning early in, if not before, pregnancy.

The prevalence of chronic deciduitis in cases of preterm labor without clinical chorioamnionitis

Preterm labor is a major cause of perinatal mortality and morbidity, and in approximately 30% of cases a clinical cause is not identified. Acute chorioamnionitis is found histologically in a significant percentage of placentas from preterm deliveries, and the mother is often asymptomatic. Although such subclinical acute chorioamnionitis is known to play a role in preterm labor, this study explores the hypothesis that chronic deciduitis with plasma cells is seen more frequently in cases of preterm labor than in control placentas. Thirty-nine singleton placentas from patients with idiopathic preterm labor were examined microscopically and compared in a blinded fashion with 39 gestational age-matched control placentas. Cases of clinical acute chorioamnionitis and known chronic maternal diseases were excluded. Thirty-nine control singleton placentas were obtained from patients undergoing induction of labor for fetal structural abnormalities, excluding aneuploidy. The presence or absence of acute chorioamnionitis, acute fetal inflammatory response, chronic deciduitis, chronic villitis, infarction, and decidual vasculopathy was noted. Immunohistochemical staining was undertaken to further define leukocyte subtypes. Forty-one percent of cases and 15% of controls showed chronic deciduitis (P = 0.022). Forty-six percent of cases and 18% of controls showed histologic acute chorioamnionitis (P = 0.015). There were 8 cases demonstrating acute fetal inflammatory response but only 1 control (P = 0.029). Little difference was seen in the distribution of lymphocyte subsets between cases and control placentas. Our findings suggest that chronic deciduitis plays a role in the etiology of some cases of preterm labor.

Blood cytokines during the perinatal period in very preterm infants: relationship of inflammatory response and bronchopulmonary dysplasia

OBJECTIVE

To evaluate the influence of chorioamnionitis (CA) on plasma cytokines and the cytokine-associated risk of bronchopulmonary dysplasia (BPD) during the perinatal period.

STUDY DESIGN

Eleven cytokines from 128 very low gestational age infants were analyzed from cord blood and from plasma at ages 1 day and 7 days after birth. The diagnosis of CA was based on histology of the placenta, fetal membranes, and umbilical cord. Neonatal risk factors were recorded.

RESULTS

In the 48 infants born with CA, high concentrations of inflammatory cytokines in cord blood decreased during the first postnatal day. Inflammatory cytokines in cord blood was associated with the severity of CA. At 1 day after birth, the concentration of interleukin (IL)-8 predicted the risk of BPD. For the 75 infants born without CA, cytokine concentrations increased after birth. For the 128 infants born with or without CA, at 1 day after birth, the concentrations of IL-8, granulocyte colony-stimulating factor, and anti-inflammatory IL-10 were associated with the risk of BPD, after adjustment for the duration of gestation and severity of respiratory distress during the first day.

CONCLUSIONS

In infants exposed to CA, insufficient inhibition of high fetal inflammatory cytokine response shortly after birth may increase the risk of BPD.

Complement activation fragment Bb in early pregnancy and spontaneous preterm birth

OBJECTIVE

The objective of this study was to determine whether an elevated level of the complement activation fragment Bb in early pregnancy was associated with spontaneous preterm birth (SPTB) at less than 34 weeks' gestation or SPTB between 34 and 37 weeks' gestation (late SPTB).

STUDY DESIGN

This was a prospective study of 784 women enrolled at less than 20 weeks' gestation.

RESULTS

Following exclusions, 13 women (1.7%) had a SPTB at less than 34 weeks' gestation and 25 (3.2%) a SPTB between 34 and 37 weeks' gestation. Women with Bb in the top quartile were 4.7 times more likely to have an SPTB less than 34 weeks' gestation as compared with women who had levels of Bb in the lower 3 quartiles (95% confidence interval [CI] 1.5-14, P = .003). There was no association between Bb and late SPTB (relative risk 0.8, 95% CI 0.3-2).

CONCLUSION

A significant relationship was found between an elevated Bb in early pregnancy and SPTB less than 34 weeks' gestation. These results suggest that inflammatory events in early pregnancy are part of the pathogenic mechanisms of this condition.

Mid-pregnancy circulating cytokine levels, histologic chorioamnionitis and spontaneous preterm birth

Some spontaneous preterm deliveries (PTD) are caused by occult infections of the fetal membranes (histologic chorioamnionitis [HCA]). High levels of infection-related markers, including some cytokines, sampled from maternal circulation in mid-pregnancy have been linked to PTD, but whether these specifically identify HCA has not been established. We have tested associations between 13 Th1, Th2 and Th17 cytokines and PTD with and without HCA in a prospective cohort study. The study sample included 926 Pregnancy Outcomes and Community Health Study subcohort women; women with medically indicated PTD or incomplete data excluded. A panel of cytokines was assessed using a multiplex assay in maternal plasma collected at 15-27 weeks of gestation. Severe HCA was scored by a placental pathologist blinded to clinical variables. Multivariable polytomous logistic regression was used to estimate adjusted odds ratios (OR) per 1 standard deviation (S.D.) increase in cytokine levels using a 5 level outcome variable: PTD <35 weeks with HCA, PTD <35 weeks without HCA, PTD 35-36 weeks with HCA, PTD 35-36 weeks without HCA, and term (referent). Interleukin (IL)-1beta, IL-2, IL-12, interferon-gamma, IL-4, IL-6 and transforming growth factor-beta were all significantly associated with PTD <35 weeks with HCA, with ORs of 1.6-2.3 per S.D. increase. None of these were associated with PTD <35 weeks without HCA or PTD 35-36 weeks with HCA. Although the tissues of origin of circulating cytokines are unclear, the observed elevations across many cytokines among women who later delivered <35 weeks with HCA may represent a robust immune response to infection within gestational tissues. These results suggest that women with HCA could be identified using relatively non-invasive means.

Patterns of cytokine profiles differ with pregnancy outcome and ethnicity

BACKGROUND

Preterm birth (PTB) is hypothesized to be an inflammatory response disease. However, no single factor alone is likely to explain PTB risk. It is more probable that coordinated networks of cytokines affect risk.

METHODS

Therefore, we examined the relationships between amniotic fluid (AF) cytokines/chemokines and related biomarkers in PTB and normal term deliveries in African Americans and Caucasians. Data were obtained from African American (41 preterm labor and 91 term labor) and Caucasian (105 preterm labor and 100 term labor) pregnant mothers. Pro-inflammatory cytokines and related molecules interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor- (TNF)-alpha, TNF soluble receptors (sTNFR1 and sTNFR2), and anti-inflammatory cytokine IL-10 that were all previously associated with PTB were studied. Correlations between biomarkers were calculated; differences of correlation coefficients between AF from African American and Caucasian samples in preterm labor and term labor were measured.

RESULTS

Multiple differences were observed between African American and Caucasian preterm and term birth groups. In term birth the strongest differences were between pro- and anti-inflammatory correlations, whereas in PTB differences were equally distributed between pro-inflammatory/anti-inflammatory and pro-inflammatory/pro-inflammatory correlations. Three correlation patterns differed significantly between AF from PTB African Americans with and without microbial invasion of the intra-amniotic cavity (MIAC); no differences were observed in Caucasians with MIAC.

CONCLUSION

Correlation analyses of cytokine measurements suggest coordinated interplay during pregnancy; significant differences exist between African Americans and Caucasians. Such analyses can serve as a means of understanding risk factors in these populations.

Visfatin/Pre-B cell colony-enhancing factor in amniotic fluid in normal pregnancy, spontaneous labor at term, preterm labor and prelabor rupture of membranes: an association with subclinical intrauterine infection in preterm parturition

OBJECTIVE

Visfatin, a novel adipokine originally discovered as a pre-B-cell colony enhancing factor, is expressed by amniotic epithelium, cytotrophoblast, and decidua and is over-expressed when fetal membranes are exposed to mechanical stress and/or pro-inflammatory stimuli. Visfatin expression by fetal membranes is dramatically up-regulated after normal spontaneous labor. The aims of this study were to determine if visfatin is detectable in amniotic fluid (AF) and whether its concentration changes with gestational age, spontaneous labor, preterm prelabor rupture of membranes (preterm PROM) and in the presence of microbial invasion of the amniotic cavity (MIAC).

METHODS

In this cross-sectional study, visfatin concentration in AF was determined in patients in the following groups: 1) mid-trimester (n=75); 2) term not in labor (n=27); 3) term in spontaneous labor (n=51); 4) patients with preterm labor with intact membranes (PTL) without MIAC who delivered at term (n=35); 5) patients with PTL without MIAC who delivered preterm (n=52); 6) patients with PTL with MIAC (n=25); 7) women with preterm PROM without MIAC (n=26); and 8) women with preterm PROM with MIAC (n=26). Non-parametric statistics were used for analysis.

RESULTS

1) The median AF concentration of visfatin was significantly higher in patients at term than in mid-trimester; 2) Among women with PTL who delivered preterm, the median visfatin concentration was significantly higher in patients with MIAC than those without MIAC; 3) Similarly, patients with PTL and MIAC had a higher median AF visfatin concentration than those with PTL who delivered at term; 4) Among women with preterm PROM, the median AF visfatin concentration was significantly higher in patients with MIAC than those without MIAC.

CONCLUSIONS

1) Visfatin is a physiologic constituent of AF; 2) The concentration of AF visfatin increases with advancing gestational age; 3) AF visfatin concentration is elevated in patients with MIAC, regardless of the membrane status, suggesting that visfatin participates in the host response against infection.

Regulation of maternal serum and amniotic fluid cytokine profiles in the mouse: Possible roles in the onset of labour

Murine pregnancy is characterised by marked increases in serum cytokine profiles with advancing gestation, but whether these changes reflect concentrations in amniotic fluid is unknown. This study therefore profiled 23 cytokines by fluid-phase multiplex immunoassay of amniotic fluid and serum collected from naturally mated mice during mid- and late pregnancy (days 11 and 18, respectively). The marked increase in serum profile of many cytokines from days 11 to 18 was not reflected in amniotic fluid, wherein most cytokine concentrations were lower on day 18. Serum and amniotic fluid cytokine concentrations were largely inversely related, indicating separate, localised regulatory mechanisms geared towards the maintenance of pregnancy, modulation of immune effector cell function and optimisation of fetal development. We suggest that, while maternal systemic inflammatory priming prepares the mother for birth, the amniotic compartment exhibits a tightly regulated inflammatory quiescence. These findings are discussed in relation to the onset of labour, which ultimately results in the elevated cytokine amniotic levels traditionally associated with the final stages of pregnancy.

The role of inflammation and infection in preterm birth

Inflammation has been implicated in the mechanisms responsible for preterm and term parturition, as well as fetal injury. Out of all of the suspected causes of preterm labor and delivery, infection and/or inflammation is the only pathological process for which both a firm causal link with preterm birth has been established and a molecular pathophysiology defined. Inflammation has also been implicated in the mechanism of spontaneous parturition at term. Most cases of histopathological inflammation and histological chorioamnionitis, both in preterm and term labor, are sub-clinical in nature. The isolation of bacteria in the amniotic fluid, known as microbial invasion of the amniotic cavity, is a pathological finding; the frequency of which is dependent upon the clinical presentation and gestational age. This article reviews the role of inflammation in preterm and term parturition.

The preterm parturition syndrome

The implicit paradigm that has governed the study and clinical management of preterm labour is that term and preterm parturition are the same processes, except for the gestational age at which they occur. Indeed, both share a common pathway composed of uterine contractility, cervical dilatation and activation of the membranes/decidua. This review explores the concept that while term labour results from physiological activation of the components of the common pathway, preterm labour arises from pathological signalling and activation of one or more components of the common pathway of parturition. The term "great obstetrical syndromes" has been coined to reframe the concept of obstetrical disease. Such syndromes are characterised by: (1) multiple aetiology; (2) long preclinical stage; (3) frequent fetal involvement; (4) clinical manifestations that are often adaptive in nature; and (5) gene-environment interactions that may predispose to the syndromes. This article reviews the evidence indicating that the pathological processes implicated in the preterm parturition syndrome include: (1) intrauterine infection/inflammation; (2) uterine ischaemia; (3) uterine overdistension; (4) abnormal allograft reaction; (5) allergy; (6) cervical insufficiency; and (7) hormonal disorders (progesterone related and corticotrophin-releasing factor related). The implications of this conceptual framework for the prevention, diagnosis, and treatment of preterm labour are discussed.

Comparison of Vaginal Cytokine Collection Methods

OBJECTIVE

The objective of our study was to correlate the interleukin-6 (IL-6) concentrations detected in patient-collected specimens with provider-collected specimens and compare the reproducibility of the methods.

STUDY DESIGN

All enrolled participants underwent pelvic examination with collection of cytokine samples by the provider and also collected samples themselves using vaginal swabs. The order of sample collection was randomly assigned. All samples were frozen at -80 degrees C for batch analysis. A commercial enzyme-linked immunosorbent assay was used to determine the concentrations of IL-6 in all samples.

RESULTS

IL-6 concentrations from wicks and swabs were correlated in a linear fashion (r = 0.67, P < 0.001). IL-6 concentrations in the two swabs (r = 0.94, P < 0.001) and the two wicks (r = 0.71, P < 0.001) were correlated in a linear fashion, although there was more variability in wick specimens.

CONCLUSION

IL-6 concentrations can be reproducibly measured using either method. The ease of patient swab collection and the correlation with provider-collected specimens may make frequent assessment of the vaginal cytokine environment more acceptable to patients.

Histological chorioamnionitis and neonatal leukemoid reaction in low-birth-weight infants

We investigated whether histological chorioamnionitis (HCA) is a risk factor predisposing to leukemoid reaction (LR) and whether LR is associated with the preterm parturition syndrome and the systemic fetal inflammation response syndrome. A prospective histological study on placentas was performed in preterm infants (<or=32(+6) weeks' gestation) admitted to level III neonatal intensive care unit of Padua University from January 1998 to December 2003. Development of LR was related to evidence of HCA. Among the placentas of the 223 preterm examined infants, 61 (27%) were diagnosed with HCA. Overall incidence of LR was 5.3%. Of 61 preterm neonates with HCA, 8 (13%) developed LR; moreover, 4 (2%) of 162 preterm infants without HCA developed LR (odds ratio = 7.4). Neonates with both LR and HCA differ from neonates with LR and without HCA in occurrence of prolonged rupture of membranes (62.5% versus 0%, P < .01), mode of delivery (37.5% versus 100% cesarean delivery, P < .01), gestational age (26 +/- 1.6 versus 29.7 +/- 1.7 gestational weeks, P < .01), and bronchopulmonary dysplasia incidence (63% versus 25%, P < .01). Histological chorioamnionitis placental findings increase the risk for neonatal LR. The LR in low-birth-weight neonates with HCA is significantly associated with earlier delivery and bronchopulmonary dysplasia. Pathogenetic mechanisms of neonatal LR in low-birth-weight infants without HCA remain undefined.

Biomarkers for the prediction of preterm delivery

This structured review discusses the current literature on selected biomarkers and their ability to predict preterm delivery (PTD). Among symptomatic women, the likelihood ratio (LR+) for the prediction of PTD was found to be greater than 10 using amniotic fluid (AF) interleukin-6 (IL-6), AF Ureaplasma urealyticum, as well as a multi-marker consisting of cervical IL-6, cervical IL-8, and cervical length (CL). The LR+ was found to be between 5 and 10 for serum C-reactive protein (CRP). An LR+ between 2.5 and 5 was recorded for serum corticotropin-releasing hormone (CRH), cervical fetal fibronectin (fFN), cervical IL-6, serum relaxin, and a multi-marker consisting of fFN and CL. CL and bacterial vaginosis (BV) both predicted PTD in women with preterm labor with an LR+ of less than 2.5. In asymptomatic women, AF U. urealyticum and a multimarker consisting of five individual markers [fFN, CL, serum alpha-fetoprotein (AFP), serum alkaline phosphatase, and serum granulocyte colony-stimulating factor (G-CSF)] predicted PTD with an LR+ greater than 10. The LR+ was between 5 and 10 for serum relaxin and CL. LRs+ recorded for serum alkaline phosphatase, salivary estriol, serum CRH, serum G-CSF, cervical IL-6, AF IL-6, cervical fFN, AFP, and Chlamydia all ranged between 2.5 and 5. Finally, an LR+ below 2.5 has been documented for serum ferritin, serum CRP, BV, and cervical ferritin.

Biochemical markers for the prediction of preterm birth

The prediction of preterm birth may be important (1) to initiate risk specific treatment; (2) to define a population that is at risk in which to study a particular treatment; or (3) to better understand the pathways that lead to preterm birth. Biologic fluids that have been used as sources for tests include serum, plasma, amniotic fluid, urine, vaginal and cervical secretions, saliva, and even periodontal fluid. We discuss the types of substances that are found in body fluids (eg, organisms, cytokines, enzymes, hormones) that have been studied as predictors of preterm birth, the fluids in which they are found, and issues that are related to the timing of the test, the cost, and the ease of fluid collection and processing. We emphasize that a test for any of these substances should not be introduced into clinical practice until the use of the test, which is followed by an appropriate intervention, leads to a reduction in preterm birth.

Risk factors for recurrent preterm delivery

OBJECTIVE

To identify risk factors for recurrent preterm delivery among primiparous women with previous preterm delivery.

STUDY DESIGN

A retrospective case-control study was designed: 152 primiparous women who delivered preterm (22-36 weeks) were divided into two groups: 81 had a second preterm delivery (study group) and 71 had a second-term delivery (control group). Exclusion criteria were induced preterm delivery, hydramnions and multiple gestations.

RESULTS

Comparing second preterm delivery before 34 weeks (n = 36) to the second delivery of the control group, higher rates of hospitalization due to preterm labor were noted in the study versus the control group (52.8% versus 16.9%,P = 0.001). The interval between pregnancies was shorter in the study subgroup, before 34 weeks gestational age, versus the controls (20.1 +/-15.7 months versus 28.9 +/- 18.7 months, P = 0.011). Multiple regression analyses, adjusted for confounding variables, found the occurrence of preterm labor and short interval between pregnancies, especially up to 12 months, as independent risk factors for the recurrence of preterm delivery (OR = 4.98; P , 0.001; OR = 5.13; P = 0.007, respectively).

CONCLUSION

When adjusted for confounding variables, short interval between pregnancies is an independent risk factor for recurrent preterm delivery.

What have we learned about vaginal infections and preterm birth?

Asymptomatic maternal genital tract infection during pregnancy, particularly bacterial vaginosis, has been consistently associated with preterm birth. In response to this evidence, the Maternal-Fetal Medicine Units Network (MFMU) designed and conducted 2 large randomized, placebo-controlled clinical trials of metronidazole treatment of asymptomatic pregnant women with bacterial vaginosis or trichomoniasis in a general obstetrical population. These studies showed that treatment of women with bacterial vaginosis failed to prevent preterm birth, regardless of their history of prior preterm birth. Metronidazole treatment of women with trichomoniasis significantly increased the risk of preterm birth compared to placebo. These results formed the basis of the US Preventive Services Task Force recommendation that screening for bacterial vaginosis not be undertaken in low-risk pregnant women, and show that MFMU network studies can have a direct and immediate impact on obstetrical practice.

Testing for risk of preterm delivery

Four discrete mechanisms for the pathogenesis of PTD have been described but they share a final common pathway. Moreover, although the mechanisms have distinct clinical characteristics, they are not mutually exclusive. As an example, triplet gestations are more likely to be associated with periconceptional intrauterine manipulations predisposing to infection, as well as fetal growth restriction, decidual hemorrhage, and pathologic uterine distention. An improved understanding of these pathologic pathways has led to the development of new tests to predict PTD. Use of multiple markers (eg, serum CRH, salivary E3, cervical IL-6, TAT, and fFN) holds promise for implementing targeted interventions to prevent PTD.

What we have learned about the predictors of preterm birth

The Preterm Prediction Study conducted by the Maternal Fetal Medicine Network between 1993 and 1996 studied a large number of risk factors for preterm birth in more than 3,000 women at 10 centers. The goals of the study were to better understand the strength of one risk factor versus another and to explore interactions among the predictors looking for combinations of factors that were more predictive of preterm birth than any single factor used alone. The most potent factors that were associated with spontaneous preterm birth at < 32 weeks were a positive cervical-vaginal fetal fibronectin test (odds ratio, 32.7) and < l0th percentile cervical length (odds ratio, 5.8), and in serum, > 90th percentiles of alpha-fetoprotein (odds ratio, 8.3) and alkaline phosphatase (odds ratio, 6.8), and > 75th percentile of granulocyte colony-stimulating factor (odds ratio, 5.5). Results for spontaneous preterm birth at < 35 weeks were generally similar but not as strong. The overlap among the strongest biologic markers for predicting spontaneous preterm birth was small. This suggests that the use of tests such as maternal alpha-fetoprotein, alkaline phosphatase, and granulocyte colony-stimulating factor as a group or adding their results to fetal fibronectin and cervical length test results may enhance our ability to predict spontaneous preterm birth and that the development of a multiple-marker test for spontaneous preterm birth is feasible.

Micronutrients and intrauterine infection, preterm birth and the fetal inflammatory response syndrome

Prematurity is the leading cause of perinatal morbidity and mortality worldwide. Intrauterine infection has emerged as a major cause of premature labor and delivery. It has been estimated that 25% of all preterm deliveries occur to mothers who have microbial invasion of the amniotic cavity, although these infections are mostly subclinical in nature. This article describes the pathways leading to intrauterine infection, microbiology, frequency and clinical consequences of infection. The pathophysiology of the fetal inflammatory response syndrome is reviewed, as is its relationship to long-term handicap, such as cerebral palsy and bronchopulmonary dysplasia. A possible role for two micronutrients, vitamins C and E, in the prevention of the preterm prelabor rupture of membranes and the consequences of fetal inflammation is considered. Research needs are listed.