Likelihood ratios for the prediction of preterm delivery with biomarkers

Preventing Preterm Birth: Exploring Innovative Solutions

This review examines the complexities of preterm birth (PTB), emphasizes the pivotal role of inflammation in the pathogenesis of preterm labor, and assesses current available interventions. Antibiotics, progesterone analogs, mechanical approaches, nonsteroidal anti-inflammatory drugs, and nutritional supplementation demonstrate a limited efficacy. Tocolytic agents, targeting uterine activity and contractility, inadequately prevent PTB by neglecting to act on uteroplacental inflammation. Emerging therapies targeting toll-like receptors, chemokines, and interleukin receptors exhibit promise in mitigating inflammation and preventing PTB.

A multisite study to develop and validate first trimester, circulating microparticle biomarkers for tiered risk stratification of spontaneous preterm birth in nulliparas

BACKGROUND

Despite much research, advances in early prediction of spontaneous preterm birth (sPTB) has been slow. The evolving field of circulating microparticle (CMP) biology may identify novel blood-based, and clinically useful, biomarkers.

OBJECTIVE

To test the ability of a previously identified, 7-marker set of CMP-derived proteins from the first trimester of pregnancy, in the form of an in vitro diagnostic multivariate index assay (IVDMIA), to stratify pregnant patients according to their risk for sPTB.

STUDY DESIGN

We employed a previously validated set of CMP protein biomarkers, utilizing mass spectrometry assays and a nested case-control design in a subset of participants from the Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be (nuMoM2b). We evaluated these biomarkers in the form of an IVDMIA to predict risk for sPTB at different gestational ages. Plasma samples collected at 9- to 13-weeks' gestation were analyzed. The IVDMIA assigned subjects to 1 of 3 sPTB risk categories: low risk (LR), moderate risk (MR), or high risk (HR). Independent validation on a set-aside set confirmed the IVDMIA's performance in risk stratification.

RESULTS

Samples from 400 participants from the nuMoM2b cohort were used for the study; of these, 160 delivered<37 weeks and 240 delivered at term. Through Monte Carlo simulation in which the validation results were adjusted based on actual weekly sPTB incidence rates in the nuMoM2b cohort, the IVDMIA stratifications demonstrated statistically significant differences among the risk groups in time-to-event (birth) analysis (P<.0001). The incidence-rate adjusted cumulative risks of sPTB at ≤32 weeks' gestation were 0.4%, 1.6%, and 7.5%, respectively for the LR, MR, and HR groups, respectively. Compared to the LR group, the corresponding risk ratios of the IVDMIA assigned MR and HR group were 4.25 (95% confidence interval [CI] 2.2-7.9) and 19.92 (95% CI 10.4-37.4), respectively.

CONCLUSION

A first trimester CMP protein biomarker panel can be used to stratify risk for sPTB at different gestational ages. Such a multitiered stratification tool could be used to assess risk early in pregnancy to enable timely clinical management and interventions, and, ultimately, to enable the development of tailored care pathways for sPTB prevention.

Biomarkers for Preterm Delivery

Preterm birth occurring before the thirty-seventh gestational week complicates 4.5%-18% of pregnancies worldwide. The pathogenesis of spontaneous preterm delivery is not fully understood. Among the factors held to be responsible for its pathogenesis, the most emphasized is the inflammatory process. Studies in terms of the prediction of preterm delivery are basically divided into 3 categories: 1) Prediction in pregnant women who are asymptomatic and without risk factors, 2) Prediction in pregnant women who are asymptomatic and have risk factors, 3) Prediction in symptomatic pregnant women who have threatened preterm labour. In this chapter, the topic of biomarkers in relation to preterm delivery is discussed. The most commonly used markers in published studies are fetal fibronectin, cervical pIGFBP-1 and cervical length measurement by transvaginal ultrasound. For prediction in symptomatic pregnant women applying to the hospital with threatened preterm labour, the markers used are fetal fibronection, insulin-like growth factors (IGFs) and inflammatory markers. Preterm labour prediction with markers checked in the first and second trimesters are fetal fibronection, insulin-like growth factors (IGFs), micro RNAs, progesterone, circulating microparticles (CMPs), inflammatory markers, matrix metalloproteinases, aneuploidy syndrome screening test parameters and other hormones.

Recurrence risk of preterm birth in a subsequent singleton pregnancy after a spontaneous preterm triplet delivery

OBJECTIVE

History of prior preterm birth (PTB) represents one of the strongest risk factors for recurrent PTB. Nevertheless, whether the occurrence of PTB in multifetal gestation is associated with increased risk of PTB in subsequent pregnancies remains unclear. We aimed to determine the recurrence risk of PTB in a subsequent singleton pregnancy after a previous spontaneous preterm triplet delivery.

STUDY DESIGN

A retrospective matched case-control study. The study group comprised all women with spontaneous preterm trichorionic triplet delivery who had a subsequent singleton pregnancy during 2006-2017 at two university hospitals. A control group of women with spontaneous preterm dichorionic twin delivery and a subsequent singleton pregnancy, was established by matching, four-to-one, according to maternal age, parity, gestational age at delivery, and delivery year.

RESULTS

Data from 170 women were analyzed, 34 with preterm triplet delivery and 136 matched control women with preterm twin delivery. Gestational age at the subsequent singleton delivery was higher in those with preterm triplet delivery than in those with preterm twin delivery (median 39 vs 38 weeks, P = 0.02). Women with prior triplet PTB had a significantly lower rate of recurrent PTB as compared with women with prior twin PTB (5.9 % vs. 25.0 %; OR [95 % CI]: 0.19 (0.04, 0.82), P = 0.02) with lower proportions of low-birth weight infants (<2500 g) (0 % vs. 11.8 %, P = 0.04).

CONCLUSIONS

The risk of recurrent PTB following spontaneous PTB in triplet pregnancy was low compared to preterm twin delivery. These data provide reassurance for those who experienced preterm triplet delivery and suggest the need for further studies to understand the mechanisms contributing to PTB in multifetal pregnancies.

Cervico-vaginal placental α-macroglobulin-1 combined with cervical length for the prediction of preterm birth in women with threatened preterm labor

INTRODUCTION

Preterm birth is a major cause of neonatal morbidity and mortality. There is an urgent need to accurately predict imminent delivery to enable necessary interventions such as tocolytic, glucocorticoid, and magnesium sulfate administration. We aimed to evaluate placental α-macroglobulin-1 as a new diagnostic marker in the prediction of preterm birth.

MATERIAL AND METHODS

We performed a prospective observational trial in women with intact membranes between 24⁺⁰ and 36⁺⁶ weeks of gestation. We included both women with and without threatened preterm labor symptoms. We evaluated the test performance of placental α-macroglobulin-1 measurements in cervicovaginal fluid regarding three different presentation-to-delivery intervals: ≤2, ≤7, ≤14 days. In addition, we calculated placental α-macroglobulin-1 performance in combination with other prognostic factors such as ultrasonographic cervical length measurements.

RESULTS

We included 126 women in the study. We detected high specificity (97%-98%) and negative predictive value (89%-97%) for placental α-macroglobulin-1 at all time intervals. We assessed placental α-macroglobulin-1 in combination with cervical length measurements (≤15 mm) in the sub-group of women presenting with threatened preterm labor symptoms (n = 63) and detected high positive predictive values (100%) for 7- and 14-day presentation-to-delivery intervals.

CONCLUSIONS

Our study provides evidence that placental α-macroglobulin-1 testing in cervicovaginal fluid, in combination with cervical length measurements, accurately predicts preterm birth in women with preterm labor symptoms. This novel test combination may be used clinically to triage women presenting with threatened preterm labor, avoiding overtreatment and unnecessary hospitalizations.

Use of metabolomics for predicting spontaneous preterm birth in asymptomatic pregnant women: protocol for a systematic review and meta-analysis

INTRODUCTION

Preterm birth (PTB) is the leading cause of neonatal mortality and short- and long-term morbidity. The aetiology and pathophysiology of spontaneous PTB (sPTB) are still unclear, which makes the identification of reliable and accurate predictor markers more difficult, particularly for unscreened or asymptomatic women. Metabolomics biomarkers have been demonstrated to be potentially accurate biomarkers for many disorders with complex mechanisms such as PTB. Therefore, we aim to perform a systematic review of metabolomics markers associated with sPTB. Our research question is 'What is the performance of metabolomics for predicting spontaneous preterm birth in asymptomatic pregnant women?'

METHODS AND ANALYSIS

We will focus on studies assessing metabolomics techniques for predicting sPTB in asymptomatic pregnant women. We will conduct a comprehensive systematic review of the literature from the last 10 years. Only observational cohort and case-control studies will be included. Our search strategy will be carried out by two independent reviewers, who will scan title and abstract before carrying out a full review of the article. The scientific databases to be explored include PubMed, MedLine, ScieLo, EMBASE, LILACS, Web of Science, Scopus and others.

ETHICS AND DISSEMINATION

This systematic review protocol does not require ethical approval. We intend to disseminate our findings in scientific peer-reviewed journal, the Preterm SAMBA study open access website, specialists' conferences and to our funding agencies.

PROSPERO REGISTRATION NUMBER

CRD42018100172.

Does neighborhood socioeconomic status predict the risk of preterm birth? A community-based Canadian cohort study

OBJECTIVE

This study developed and internally validated a predictive model for preterm birth (PTB) to examine the ability of neighbourhood socioeconomic status (SES) to predict PTB.

DESIGN

Cohort study using individual-level data from two community-based prospective pregnancy cohort studies (All Our Families (AOF) and Alberta Pregnancy Outcomes and Nutrition (APrON)) and neighbourhood SES data from the 2011 Canadian census.

SETTING

Calgary, Alberta, Canada.

PARTICIPANTS

Pregnant women who were <24 weeks of gestation and >15 years old were enrolled in the cohort studies between 2008 and 2012. Overall, 5297 women participated in at least one of these cohorts: 3341 women participated in the AOF study, 2187 women participated in the APrON study and 231 women participated in both studies. Women who participated in both studies were only counted once.

PRIMARY AND SECONDARY OUTCOME MEASURES

PTB (delivery prior to 37 weeks of gestation).

RESULTS

The rates of PTB in the least and most deprived neighbourhoods were 7.54% and 10.64%, respectively. Neighbourhood variation in PTB was 0.20, with an intra-class correlation of 5.72%. Neighbourhood SES, combined with individual-level predictors, predicted PTB with an area under the receiver-operating characteristic curve (AUC) of 0.75. The sensitivity was 91.80% at a low-risk threshold, with a high false-positive rate (71.50%), and the sensitivity was 5.70% at a highest risk threshold, with a low false-positive rate (0.90%). An agreement between the predicted and observed PTB demonstrated modest model calibration. Individual-level predictors alone predicted PTB with an AUC of 0.60.

CONCLUSION

Although neighbourhood SES combined with individual-level predictors improved the overall prediction of PTB compared with individual-level predictors alone, the detection rate was insufficient for application in clinical or public health practice. A prediction model with better predictive ability is required to effectively find women at high risk of preterm delivery.

Effectiveness and Accuracy of Tests for Preterm Delivery in Symptomatic Women: A Systematic Review

This study systematically reviewed evidence on the effectiveness and accuracy of predictive tests for preterm delivery among symptomatic women. The study included English-language systematic reviews (SRs) on any predictive test for preterm delivery among symptomatic women and primary studies for placental alpha-microglobulin-1. PubMed, Wiley Cochrane Library, the Centre for Reviews and Dissemination Database, the National Guidelines Clearinghouse, and the TRIP database were searched for SRs, PubMed and PubMed Central via the Wiley Cochrane Library were searched for primary studies. One reviewer performed study selection, with input from a second reviewer when needed. One reviewer appraised study quality and extracted: study characteristics (i.e., country, funding source, study design [primary studies] or synthesis method [SRs], study appraisal method [SRs]), population characteristics, index test(s) and cut-off points used, comparator(s) or reference standard(s), and outcomes. A second reviewed a random 10% sample. The authors synthesized the findings narratively. Of 451 unique records, the review included 22 (17 SRs, five primary studies). For effectiveness, there was evidence for use of transvaginal sonographic cervical length assessment (15-25 mm cut point) in reducing incidence of preterm delivery at <37 weeks (relative risk 0.64; 95% CI 0.44-0.94, one SR of three trials; n = 287) but lack of support for cervicovaginal fetal fibronectin. In terms of accuracy, one high-quality study within a best-evidence SR showed that cervical length measurement was useful to predict delivery within 48 hours (LR+ 6.43, 95% CI 5.17-8.00; LR- 0.03, 95% CI 0.00-0.42; n = 510) and 7 days (LR+ 8.61, 95% CI 6.65-11.14; LR- 0.03, 95% CI 0.00-0.18; n = 510). Accuracy of placental alpha-microglobulin-1 testing was not supported for most end points. In conclusion, some evidence supports the effectiveness of cervical length as a predictor of preterm delivery in symptomatic women. Evidence for most tests is limited in quality and quantity.

The diagnostic accuracy of the Ascertain Dementia 8 questionnaire for detecting cognitive impairment in primary care in the community, clinics and hospitals: a systematic review and meta-analysis

Background

The prevalence of cognitive impairment is increasing due to the aging population, and early detection is essential clinically. The Ascertain Dementia 8 (AD8) questionnaire is a brief informant-based measure recently developed to assess early cognitive impairment, however, its overall diagnostic performance is controversial. The objective of this meta-analysis was to assess the diagnostic accuracy of the AD8 for cognitive impairment.

Methods

All relevant studies were collected from databases including MEDLINE, EMBASE and the Cochrane Library up to April 2017. We used QUADAS-2 to assess the methodological quality after the systematic search. The accuracy data and potential confounding variables were extracted from the eligible studies which included those in English and non-English. All analyses were performed using the Midas module in Stata 14.0 and Meta-DiSc 1.4 software.

Results

Seven relevant studies including 3728 subjects were collected, and classified into two subgroups according to the severity of cognitive impairment. The overall sensitivity (0.72, 0.91) was superior to specificity (0.67, 0.78). The pooled negative likelihood ratio (0.17, 0.13) was better than the positive likelihood ratio (2.52, 3.94). The areas under the summary receiver operating characteristic curve were 0.83 and 0.92, respectively. Meta-regression analysis showed that location (community versus non-community) may be the source of heterogeneity. The average administration time was less than 3 minutes.

Conclusion

Our findings suggest that the AD8 is a competitive tool for clinically screening cognitive impairment and has an optimal administration time in the busy primary care setting. Subjects with an AD8 score ≧2 should be highly suspected to have cognitive impairment and a further definite diagnosis is needed.

Mid-gestational changes in cervicovaginal fluid cytokine levels in asymptomatic pregnant women are predictive markers of inflammation-associated spontaneous preterm birth

OBJECTIVES

Perturbation of the choriodecidual space before the onset of spontaneous preterm birth (sPTB) could lead to a concomitant rise in both cervicovaginal fluid (CVF) cytokine and fetal fibronectin (FFN), and assessing the concentrations of both markers could improve the prediction of sPTB (delivery before 37 completed weeks of gestation). Therefore, we prospectively determined mid-trimester changes in CVF cytokine and FFN concentrations, and their predictive capacity for sPTB in asymptomatic pregnant women.

STUDY DESIGN

CVF collected at 20+0-22+6 weeks (n = 47: Preterm-delivered = 22, Term-delivered = 25) and 26+0-28+6 weeks (n = 50: Preterm-delivered = 17, Term-delivered = 33) from 63 asymptomatic pregnant women at risk of sPTB were examined. Cytokine and FFN concentrations were determined by multiplexed bead-based immunoassay and 10Q Rapid analysis (Hologic, MA, USA) respectively. The 20+0-22+6/26+0-28+6 weeks ratios of cytokines and FFN concentrations were compared between preterm- and term-delivered women using Receiver Operating Characteristics curves to predict sPTB. Also, bacterial 16S rDNA from 64 samples (20+0-22+6 weeks n = 36, 26+0-28+6 weeks n = 28) was amplified by polymerase chain reaction to determine associations between vaginal microflora, cytokine and FFN concentrations.

RESULTS

Changes in RANTES and IL-1β concentrations between 20+0-22+6 and 26+0-28+6 weeks, expressed as a ratios, were predictive of sPTB, RANTES (AUC = 0.82, CI = 0.62-0.94) more so than IL-1β (AUC = 0.71, CI = 0.53-0.85) and FFN (not predictive). Combining these markers (AUC = 0.83, CI = 0.63-0.95) showed similar predictive capacity as RANTES alone. FFN concentrations at 26+0-28+6 weeks correlated with IL-1β (r = 0.4, P = 0.002) and RANTES (r = 0.3, P = 0.03). In addition, there was increased prevalence of vaginal anaerobes including Bacteroides, Fusobacterium and Mobiluncus between gestational time points in women who experienced sPTB compared to the term women (P = 0.0006).

CONCLUSIONS

CVF RANTES and IL-1β in mid-trimester of pregnancy correlate with quantitative FFN. The levels of CVF RANTES and IL-1β decline significantly in women who deliver at term unlike women who deliver preterm. This observation suggests that sPTB may be characterised by sustained choriodecidual inflammation and may have clinical value in serial screening for sPTB if confirmed by larger studies.

Biomarkers for predicting spontaneous preterm birth: an umbrella systematic review

OBJECTIVE

To identify all systematic reviews investigating the role of maternal and fetal biomarkers for predicting spontaneous preterm birth (SPTB).

METHODS

Medline and Web of Sciences databases were searched electronically. Studies exploring the association between maternal biomarkers and spontaneous delivery were considered suitable for inclusion. A synthesis of the systematic reviews was performed with the umbrella methodology. Statistical measures of association (Odd ratio, OR, relative risk, RR) and predictive accuracy (sensitivity, specificity, positive and negative likelihood ratios were used to synthesize results of the included studies.

RESULTS

21,614 articles were identified, 542 were assessed with respect to their eligibility for inclusion and 14 systematic reviews included. Cervical fibronectin was the biomarkers which showed the highest strength of association with the occurrence of SPTB (delivery within 24 h OR 7, 95%CI 3-17; delivery <7 days (OR 12, 95%CI 8-16). Maternal serum alpha fetoprotein, was associated with an OR of 4 and 3 for early and late SPTB. C-reactive protein had an OR of 2 (95%CI 1-2) and 8 (95%CI 4-16) when detected in maternal plasma and amniotic fluid, respectively. Among cytokines, interleukin-6 had an OR and an LR + for SPTB of 2 and 12 when detected in maternal serum.

CONCLUSIONS

Cervical fetal fibronectin, alpha fetoprotein, C- reactive protein and interleukin 6 can have an overall good diagnostic accuracy in identifying pregnancies at risk of SPTB. Large prospective studies in different sub-set of women are needed to ascertain whether the combination of different serological and imaging marker can improve antenatal prediction of this condition.

The role of serial measurements of cervical length in asymptomatic women with triplet pregnancy

OBJECTIVE

To assess the predictive accuracy of serial measurements of cervical length (CL) for preterm birth in asymptomatic women with triplet pregnancy.

METHODS

A retrospective study of women with triplets who underwent serial sonographic measurements of CL until 28-32 weeks of gestation. The predictive accuracy of CL for preterm birth was determined at 4 periods along gestation: 18-20 weeks (period 1), 21-24 weeks (period 2), 25-27 weeks (period 3) and 28-32 weeks (period 4).

RESULTS

A total of 431 measurements of CL from were analyzed. CL decreased in a linear manner across gestation: 40.8 ± 7.1 mm, 36.5 ± 8.4 mm, 29.9 ± 11.4 mm and 25.0 ± 11.8 mm in periods 1, 2, 3 and 4, respectively. The difference in CL between women who did and did not deliver prematurely was small before 25 weeks (periods 1&2) but became more pronounced later in pregnancy (periods 3&4), mainly due to a rapid cervical shortening between periods 2 and 3 (shortening rate -29.0 ± 20.0% vs. -12.6 ± 20.5%, respectively, p = .01). The best predictors of preterm birth were either a single measurement of CL during period 3 or the degree of cervical shortening between periods 2 and 3.

CONCLUSIONS

Care providers should be aware of the limited predictive value of cervical length before 25 + 0 weeks in triplet pregnancies.

Early- or mid-trimester amniocentesis biomarkers for predicting preterm delivery: a meta-analysis

OBJECTIVE

To determine the value of early- or mid-trimester amniotic fluid levels of interleukin-6 (IL-6), matrix metalloproteinase-8 (MMP-8), and glucose for predicting preterm delivery.

METHODS

Randomized controlled trials and two-arm prospective, retrospective, cohorts, and case-controlled studies in which patients received early- or mid-trimester amniocentesis for karyotyping, and biomarker testing of the amniotic fluid was performed and delivery data were available were included in the analysis.

RESULTS

Outcome measures were the associations of amniotic fluid IL-6, MMP-8, and glucose levels with preterm delivery. Differences in means with 95% confidence intervals (CIs) were calculated. Of 288 articles identified, 14 were included in the meta-analysis with a total of 675 patients who had preterm birth and 2518 patients who had term births. The preterm-delivery group had significantly higher amniotic fluid IL-6 and MMP-8 levels, and a significantly lower glucose level than the term delivery group (IL-6: difference in means = 0.32, 95% CI: 0.22-0.43, p < 0.001; MMP-8: difference in means = 4.47, 95% CI: 0.83-8.11), p = 0.016; glucose: difference in means = -5.22, 95% CI: -8.19 to -2.26, p = 0.001) Conclusion: Early- or mid-trimester amniotic fluid IL-6, MMP-8, and glucose levels are useful for predicting the risk of preterm delivery. KEY MESSAGES Median amniotic fluid ferritin and IL-6 levels, and mean amniotic fluid ALP levels were higher in the preterm group. The preterm-delivery group had significantly higher amniotic fluid IL-6 and MMP-8 levels, and a significantly lower glucose level than the term-delivery group.

Diagnostic Performance of Fas Ligand mRNA Expression for Acute Rejection after Kidney Transplantation: A Systematic Review and Meta-Analysis

Background

The value of Fas ligand (FASL) as a diagnostic immune marker for acute renal rejection is controversial; this meta-analysis aimed to clarify the role of FASL in acute renal rejection.

Methods

The relevant literature was included by systematic searching the MEDLINE, EMBASE, and Cochrane Library databases. Accuracy data for acute rejection (AR) and potential confounding variables (the year of publication, area, sample source, quantitative techniques, housekeeping genes, fluorescence staining, sample collection time post-renal transplantation, and clinical classification of AR) were extracted after carefully reviewing the studies. Data were analyzed by Meta-DiSc 1.4, RevMan 5.0, and the Midas module in Stata 11.0 software.

Results

Twelve relevant studies involving 496 subjects were included. The overall pooled sensitivity, specificity, positive likelihood ratio (LR), negative LR, and diagnostic odds ratio, together with the 95% CI were 0.64 (0.57–0.70), 0.90 (0.85–0.93), 5.66 (3.51–9.11), 0.30 (0.16–0.54), and 30.63 (14.67–63.92), respectively. The area under the summary receiver operating characteristic curve (AUC) was 0.9389. Fagan’s nomogram showed that the probability of AR episodes in the kidney transplant recipient increased from 15% to 69% when FASL was positive, and was reduced to 4% when FASL was negative. No threshold effect, sensitivity analyses, meta-regression, and subgroup analyses based on the potential variables had a significant statistical change for heterogeneity.

Conclusions

Current evidence suggests the diagnostic potential for FASL mRNA detection as a reliable immune marker for AR in renal allograft recipients. Further large, multicenter, prospective studies are needed to validate the power of this test marker in the non-invasive diagnosis of AR after renal transplantation.

The greater risk of preterm birth in triplets is mirrored by a more rapid cervical shortening along gestation

BACKGROUND

The risk of preterm birth increases with plurality. However, data are limited about the role of cervical length in triplet pregnancies and how the greater predisposition for preterm birth in triplet pregnancies, compared with twin pregnancies, is reflected by cervical length. Specifically, it is unclear whether the greater predisposition of triplet pregnancies for preterm birth is reflected by a more rapid cervical shortening during gestation compared with twin pregnancies (and therefore a shorter cervical length at any given gestational age), by a greater risk for preterm birth per given cervical length at any given gestational age, or both.

OBJECTIVE

The purpose of the study was to compare the rate of cervical shortening during gestation and the correlation between cervical length and gestational age at birth in asymptomatic women with triplet vs twin pregnancies.

STUDY DESIGN

This was a retrospective study of women with triplet or twin pregnancies who were who were observed in a tertiary center who underwent serial sonographic measurement of cervical length from 16-32 weeks gestation. Change in cervical length during gestation and relationship of cervical length with gestational age at birth were compared between the triplets and twins groups.

RESULTS

A total of 431 measurements of cervical length from 86 women with triplets was analyzed and compared with 2826 measurements of cervical length from 441 women with twins. The rate of cervical shortening among triplet pregnancies was higher than among twin pregnancies starting from 18 weeks of gestation (slope of regression line, -1.297 vs -0.907; P < .001). Similarly, the proportion of women with cervical length of <25 mm or 15 mm was higher among triplet pregnancies than among twin pregnancies (34.0% vs 21.0% [P < .001] and 16.7% vs 8.4% [P = .001]), respectively. For any given cervical length measured after 22 weeks of gestation, the associated gestational length at birth in triplet pregnancies was lower by 2.7 weeks on average compared with twin pregnancies (P < .001).

CONCLUSION

The higher rate of preterm birth in triplet pregnancies, compared with twin pregnancies, is reflected by both a more rapid cervical shortening during gestation and a lower gestational age at birth per any given cervical length.

A Meta-analysis of the Significance of Granzyme B and Perforin in Noninvasive Diagnosis of Acute Rejection After Kidney Transplantation

BACKGROUND

Previous studies have reported that granzyme B (GZMB) and perforin (PRF) could serve as noninvasive biomarkers in the diagnosis of acute rejection (AR) after kidney transplant. Yet, their noninvasive diagnostic value in clinical practice is still unknown.

METHODS

To assess the noninvasive diagnostic performance of GZMB and PRF for AR, we performed a systematic search. After reviewing published studies in which both GZMB and PRF were detected, data on the diagnostic accuracy of separate and combined evaluation of GZMB and PRF were pooled.

RESULTS

Across 16 studies (680 subjects), summary sensitivity, specificity, positive likelihood ratios, and negative likelihood ratios with 95% confidence intervals were calculated. For overall GZMB analysis, the indices were 0.76 (0.71-0.81), 0.86 (0.82-0.89), 4.58 (3.36-6.25), and 0.32 (0.22-0.47), respectively. For overall PRF analysis, the indices were 0.83 (0.78-0.88), 0.86 (0.82-0.89), 4.82 (3.66-6.35), and 0.26 (0.18-0.37), respectively. Subgroup analyses showed similar results compared to overall study analyses. In analyses of combined evaluation of GZMB and PRF, the above indices were 0.65 (0.53-0.76), 0.96 (0.91-0.98), 12.66 (5.83-27.50), and 0.40 (0.23-0.69), respectively, when both markers were positive. The probability of developing AR in kidney transplant recipients increased from 15% to 73% when both GZMB and PRF tests were positive and was reduced to 2% if that were negative.

CONCLUSIONS

Currently, neither GZMB nor PRF, if evaluated alone, could be a convincing noninvasive diagnostic marker for AR in clinical practice. Combined use of PRF and GZMB post-kidney transplant may be a better choice in AR evaluation to direct allograft biopsy execution and earlier therapeutic intervention.

A proposed bio-panel to predict risk for spontaneous preterm birth among African American women

Preterm birth (PTB), or birth prior to 37 weeks gestation, impacts 11.5% of U.S. deliveries. PTB results in significant morbidity and mortality among affected children and imposes a large societal financial burden. Racial disparities in PTB are alarming. African American women are at more than 1.5 times the risk for PTB than white women. Unfortunately, the medical community's ability to predict who is at risk for PTB is extremely limited. History of a prior PTB remains the strongest predictor during a singleton gestation. Cervical length and fetal fibronectin measurement are helpful tools. However, usefulness is limited, particularly among the 95% of U.S. women currently pregnant and lacking a history of PTB. Therefore, preventive therapies do not reach a great number of women who may benefit from them. This manuscript, in response to the pressing need for predictors of PTB risk and elimination of racial disparities in PTB, presents a proposed bio-panel for use in predicting risk for spontaneous PTB among African American women. This bio-panel, measured each trimester, includes stimulated production of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-1 receptor antagonist (Ra), soluble(s) TNF receptor(R) 1, and sTNFR2, and cortisol responsiveness. We hypothesize that greater IL-1β and TNF-α production, decreased IL-1Ra, sTNFR1, and sTNFR2 production, and decreased cortisol responsiveness at each time point as well as a more expedient alignment with this unfavorable profile over time will be associated with PTB. The choice to focus on inflammatory parameters is supported by data highlighting a crucial role for inflammation in labor. Specific inflammatory mediators have been chosen due to their potential importance in preterm labor among African American women. The bio-panel also focuses on inflammatory regulation (i.e., cytokine production upon ex vivo stimulation), which is hypothesized to provide insight into potential in vivo leukocyte responses and potential for initiation of a preterm inflammatory cascade. Production of receptor antagonists is also considered, as pro-inflammatory mediator effects can be greatly influenced by their balance with respective antagonists. Finally, leukocyte responsiveness to cortisol is included as a measure of cortisol's ability to convey anti-inflammatory signals. The development of a bio-panel predictive of risk for spontaneous PTB among African American women would represent a significant advancement. Available preventive therapies, namely progesterone supplementation, could be delivered to women deemed at risk. Further, the identification of biological predictors of PTB may uncover novel targets for preventive therapies.

Predictive value of cervical length in women with twin pregnancy presenting with threatened preterm labor

OBJECTIVE

To assess the accuracy and determine the optimal threshold of sonographic cervical length (CL) for the prediction of preterm delivery (PTD) in women with twin pregnancies presenting with threatened preterm labor (PTL).

METHODS

This was a retrospective study of women with twin pregnancies who presented with threatened PTL and underwent sonographic measurement of CL in a tertiary center. The accuracy of CL in predicting PTD in women with twin pregnancies was compared with that in a control group of women with singleton pregnancies.

RESULTS

Overall, 218 women with a twin pregnancy and 1077 women with a singleton pregnancy, who presented with PTL, were included in the study. The performance of CL as a predictive test for PTD was similar in twins and singletons, as reflected by the similar correlation between CL and the examination-to-delivery interval (r, 0.30 vs 0.29; P = 0.9), the similar association of CL with risk of PTD, and the similar areas under the receiver-operating characteristics curves for differing delivery outcomes (range, 0.653-0.724 vs 0.620-0.682, respectively; P = 0.3). The optimal threshold of CL for any given target sensitivity or specificity was lower in twin than in singleton pregnancies. However, in order to achieve a negative predictive value of 95%, a higher threshold (28-30 mm) should be used in twin pregnancies. Using this twin-specific CL threshold, women with twins who present with PTL are more likely to have a positive CL test, and therefore to require subsequent interventions, than are women with singleton pregnancies with PTL (55% vs 4.2%, respectively).

CONCLUSION

In women with PTL, the performance of CL as a test for the prediction of PTD is similar in twin and singleton pregnancies. However, the optimal threshold of CL for the prediction of PTD appears to be higher in twin pregnancies, mainly owing to the higher baseline risk for PTD in these pregnancies.

Is measurement of cervical length an accurate predictive tool in women with a history of preterm delivery who present with threatened preterm labor?

OBJECTIVE

To determine whether sonographically measured cervical length is an effective predictive tool in women with threatened preterm labor and a history of past spontaneous preterm delivery.

METHODS

This was a retrospective cohort study of all women with singleton pregnancies who presented with preterm labor at less than 34 + 0 weeks' gestation and underwent sonographic measurement of cervical length in a tertiary medical center between 2007 and 2012. The accuracy of cervical length in predicting preterm delivery was compared between women with and those without a history of spontaneous preterm delivery. Women with risk factors for preterm delivery other than a history of preterm delivery were excluded from both groups.

RESULTS

Overall, 1023 women who presented with preterm labor met the study criteria, of whom 136 (13.3%) had a history of preterm delivery (past-PTD group) and 887 (86.7%) had no risk factors for preterm delivery (low-risk group). The rate of preterm delivery was significantly higher for women with a history of preterm delivery (36.8% vs 22.5%; P < 0.001). Cervical length was significantly correlated with the examination-to-delivery interval in low-risk women (r = 0.32, P < 0.001) but not in women who had had a previous preterm delivery (r = 0.07, P = 0.4). On multivariable analysis, cervical length was independently associated with the risk of preterm delivery for women in the low-risk group but not for women with a history of previous preterm delivery. For women with previous preterm delivery who presented with threatened preterm labor, cervical length failed to distinguish between those who did and those who did not deliver prematurely (area under the receiver-operating characteristics curve range, 0.475-0.506). When using standardized thresholds, the sensitivity and specificity of cervical length for the prediction of preterm delivery were significantly lower in women with previous preterm delivery than in women with no risk factors for preterm delivery.

CONCLUSION

Cervical length appears to be of limited value in the prediction of preterm delivery among women with threatened preterm labor who are at high risk for preterm delivery owing to a history of spontaneous preterm delivery in a previous pregnancy.

The resistance analysis of Ureaplasma urealyticum and Mycoplasma hominis in female reproductive tract specimens

The aim of this study was to analyze the drug resistance of Ureaplasma urealyticum (Uu) and Mycoplasma hominis (Mh) in female reproductive track from 2007 to 2011 in Hangzhou. Antibiotics sensitivity test in Mycoplasma, which was isolated in clinics from 2007 to 2011 were analyzed retrospectively. The detection of Mycoplasma during 2007-2011 was 20,146 (54.37 %), of which the single infection rate of Uu was 42.08 %, of Mh 1.26 %, and of Uu+Mh was 11.02 %. The drug resistance rate of Uu was increased significantly in ofloxacin in 2007 (41.80 %), 2008 (45.94 %), 2009 (46.07 %), 2010 (50.36 %), and 2011 (53.22 %) (P < 0.05). The resistance rate to ciprofloxacin was significantly increased in 2007 (67.15 %), 2008 (67.44 %), 2009 (73.00 %), 2010 (75.28 %), and 2011 (75.28 %) (P < 0.05). Exceptionally, the resistance rates of the other antibiotics were low. The drug resistance rate of Uu was significantly increased with quinolones at increasing tendency. It is necessary to monitor the local drug resistance rate of Uu regularly to provide reasonable guidelines in clinics.

Inflammatory markers in the second trimester prior to clinical onset of preeclampsia, intrauterine growth restriction, and spontaneous preterm birth

Low-grade inflammation has been associated with pregnancy complications including preeclampsia (PE), intrauterine growth restriction (IUGR), and spontaneous preterm birth (SPB). In an unmatched, nested case-control study, we assessed the possible predictive association of maternal C-reactive protein (CRP), interferon-γ-inducible protein 10 (IP-10), and soluble urokinase plasminogen activator receptor (suPAR) in second trimester plasma samples in relation to later development of PE (n = 29), IUGR (n = 53), and SPB (n = 9). Inflammatory marker levels in these groups were compared to normotensive healthy pregnant controls (n = 127). We found no statistically significant difference in CRP, IP-10, or suPAR in second trimester plasma samples from pregnant women with later PE, IUGR, and SPB when compared to normotensive healthy controls. Second trimester plasma samples of CRP, IP-10, and suPAR cannot be used as a prognostic marker for PE, IUGR, and SPB.

Cervical strain determined by ultrasound elastography and its association with spontaneous preterm delivery

OBJECTIVE

To determine if there is an association between cervical strain, evaluated using ultrasound elastography, and spontaneous preterm delivery (sPTD) <37 weeks of gestation.

METHODS

One hundred and eighty nine (189) women at 16-24 weeks of gestation were evaluated. Ultrasound elastography was used to estimate cervical strain in three anatomical planes: one mid-sagittal in the same plane used for cervical length measurement, and two cross sectional images: one at the level of the internal cervical os, and the other at the level of the external cervical os. In each plane, two regions of interest (endocervix and entire cervix) were examined; a total of six regions of interest were evaluated.

RESULTS

The prevalence of sPTD was 11% (21/189). Strain values from each of the six cervical regions correlated weakly with cervical length (from r=-0.24, P<0.001 to r=-0.03, P=0.69). Strain measurements obtained in a cross sectional view of the internal cervical os were significantly associated with sPTD. Women with strain values ≤25th centile in the endocervical canal (0.19) and in the entire cervix (0.14) were 80% less likely to have a sPTD than women with strain values >25th centile [endocervical: odds ratio (OR) 0.2; 95% confidence interval (CI), 0.03-0.96; entire cervix: OR 0.17; 95% CI, 0.03-0.9]. Additional adjustment for gestational age, race, smoking status, parity, maternal age, pre-pregnancy body mass index, and previous preterm delivery did not appreciably alter the magnitude or statistical significance of these associations. Strain values obtained from the external cervical os and from the sagittal view were not associated with sPTD.

CONCLUSION

Low strain values in the internal cervical os were associated with a significantly lower risk of spontaneous preterm delivery <37 weeks of gestation.

Biomarkers and cervical length to predict spontaneous preterm birth in asymptomatic high-risk women

OBJECTIVE

To investigate whether biomarkers from different pathways of spontaneous preterm birth (cervical membrane degradation [fetal fibronectin], cervical remodeling [soluble E-cadherin], and inflammation (elafin, surfactant protein-D, interleukin-6 [IL-6]) were superior to one biomarker alone in predicting preterm birth. Our secondary objective was to examine the association of these biomarkers with cervical length in predicting preterm birth.

METHODS

We performed a single-center, prospective cohort study from August 2011 to November 2012 of asymptomatic women at risk for spontaneous preterm birth as a result of obstetric and gynecologic history. Cervicovaginal fluid and cervical length measurements were collected at two time points (20-23 6/7 weeks and 24-27 6/7 weeks of gestation).

RESULTS

Among the 104 women with complete data, the preterm birth rate was 24.5%. Prior preterm birth (P=.006) and cervical length at visit 1 (P=.003) were significantly associated with preterm birth, whereas fetal fibronectin and median biomarker levels (elafin, soluble E-cadherin, IL-6) were not. Median surfactant protein-D levels at visit 1 by preterm birth status were statistically but not clinically different (0.44 ng/mL compared with 0.40 ng/mL, P<.001). Analyses of biomarkers from more than one pathway were not superior to single biomarker analyses in predicting prematurity. Neither inclusion of biomarkers nor fetal fibronectin improved the predictive ability of cervical length alone.

CONCLUSION

Cervical length assessment and obstetric history but not fetal fibronectin or biomarkers were useful in the risk stratification of women identified to be at greatest risk for spontaneous preterm birth.

LEVEL OF EVIDENCE

II.

Chorioamnionitis and lung injury in preterm newborns

There is a strong evidence that histologic chorioamnionitis is associated with a reduction of incidence and severity of respiratory distress syndrome (RDS). Short-term maturational effects on the lungs of extremely premature infants seem to be, however, accompanied by a greater susceptibility of the lung, eventually contributing to an increased risk of bronchopulmonary dysplasia (BPD). Genetic susceptibility to BPD is an evolving area of research and several studies have directly related the risk of BPD to genomic variants. There is a substantial heterogeneity across the studies in the magnitude of the association between chorioamnionitis and BPD, and whether or not the association is statistically significant. Considerable variation is largely dependent on differences of inclusion and exclusion criteria, as well as on clinical and histopathological definitions. The presence of significant publication bias may exaggerate the magnitude of the association. Controlling for publication bias may conduct to adjusted results that are no longer significant. Recent studies generally seem to confirm the effect of chorioamnionitis on RDS incidence, while no effect on BPD is seen. Recent data suggest susceptibility for subsequent asthma to be increased on long-term followup. Additional research on this field is needed.

The clinical significance of a positive Amnisure test in women with preterm labor and intact membranes

OBJECTIVE

This study was conducted to examine the frequency and clinical significance of a positive Amnisure test in patients with preterm labor and intact membranes by sterile speculum exam.

STUDY DESIGN

A retrospective cohort study was performed including 90 patients with preterm labor and intact membranes who underwent Amnisure tests prior to amniocentesis (< 72 h); most patients (n=64) also underwent fetal fibronectin (fFN) tests. Amniotic fluid (AF) was cultured for aerobic/anaerobic bacteria and genital mycoplasmas and assayed for matrix metalloproteinase-8.

RESULTS

(1) the prevalence of a positive Amnisure test was 19% (17/90); (2) patients with a positive Amnisure test had significantly higher rates of adverse pregnancy and neonatal outcomes (e.g., impending preterm delivery, intra-amniotic infection/inflammation, and neonatal morbidity) than those with a negative Amnisure test; (3) a positive test was associated with significantly increased risk of intra-amniotic infection and/or inflammation, delivery within 7, 14, or 28 days and spontaneous preterm birth (< 35 weeks) among patients with a negative fFN test.

CONCLUSIONS

A positive Amnisure test in patients with preterm labor and intact membranes is a risk factor for adverse pregnancy outcome, particularly in patients with a negative fFN test. A positive Amnisure test in patients without symptoms or signs of ROM should not be taken as an indicator that membranes have ruptured.

Perinatal inflammation and lung injury

Bronchopulmonary dysplasia (BPD) remains the major morbidity of extreme preterm birth. The incidence of BPD has remained stable despite recent efforts to reduce postnatal exposures to volutrauma and hyperoxia. This review will focus on recent clinical and experimental insights that provide support for the concept that the 'new BPD' is the result of inflammation-mediated injury and altered lung development during a window of vulnerability in genetically susceptible infants that is modified by maternal and postnatal exposures.