Development and validation of a tool incorporating quantitative fetal fibronectin to predict spontaneous preterm birth in symptomatic women

Preterm Birth: Screening and Prediction

Preterm birth (PTB) affects approximately 10% of births globally each year and is the most significant direct cause of neonatal death and of long-term disability worldwide. Early identification of women at high risk of PTB is important, given the availability of evidence-based, effective screening modalities, which facilitate decision-making on preventative strategies, particularly transvaginal sonographic cervical length (CL) measurement. There is growing evidence that combining CL with quantitative fetal fibronectin (qfFN) and maternal risk factors in the extensively peer-reviewed and validated QUanititative Innovation in Predicting Preterm birth (QUiPP) application can aid both the triage of patients who present as emergencies with symptoms of preterm labor and high-risk asymptomatic women attending PTB surveillance clinics. The QUiPP app risk of delivery thus supports shared decision-making with patients on the need for increased outpatient surveillance, in-patient treatment for preterm labor or simply reassurance for those unlikely to deliver preterm. Effective triage of patients at preterm gestations is an obstetric clinical priority as correctly timed administration of antenatal corticosteroids will maximise their neonatal benefits. This review explores the predictive capacity of existing predictive tests for PTB in both singleton and multiple pregnancies, including the QUiPP app v.2. and discusses promising new research areas, which aim to predict PTB through cervical stiffness and elastography measurements, metabolomics, extracellular vesicles and artificial intelligence.

Prevention and Therapy of Preterm Birth. Guideline of the DGGG, OEGGG and SGGG (S2k-Level, AWMF Registry Number 015/025, September 2022) - Part 1 with Recommendations on the Epidemiology, Etiology, Prediction, Primary and Secondary Prevention of Preterm Birth

Aim This revised guideline was coordinated by the German Society for Gynecology and Obstetrics (DGGG), the Austrian Society for Gynecology and Obstetrics (OEGGG) and the Swiss Society for Gynecology and Obstetrics (SGGG). It aims to improve the prediction, prevention, and management of preterm birth, based on evidence from the current literature, the experience of members of the guidelines commission, and the viewpoint of self-help organizations. Methods The members of the contributing professional societies and organizations developed recommendations and statements based on international literature. The recommendations and statements were presented and adopted using a formal process (structured consensus conferences with neutral moderation, written Delphi vote). Recommendations Part 1 of this short version of the guideline presents statements and recommendations on the epidemiology, etiology, prediction, and primary and secondary prevention of preterm birth.

Preterm labor with intact membranes: a simple noninvasive method to identify patients at risk for intra-amniotic infection and/or inflammation

OBJECTIVE

To develop a noninvasive scoring system to identify patients at high risk for intra-amniotic infection and/or inflammation, which would reduce the need for amniocentesis.

METHODS

This prospective cohort study comprised patients admitted with preterm labor and intact membranes (20-34 weeks of gestation) who underwent a transabdominal amniocentesis and for whom concentrations of quantitative cervical fetal fibronectin and of maternal serum C-reactive protein (CRP) were determined. Intra-amniotic infection was defined as a positive amniotic fluid culture for microorganisms. Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. Multivariate logistic regression analysis was performed to identify intra-amniotic infection/inflammtion with noninvasive parameters that had a significant relationship with univariate analysis. With four parameters identified by multivariate analysis, we generated a noninvasive risk scoring system.

RESULTS

Of the study population consisting of 138 singleton pregnant women, (1) the overall rate of intra-amniotic infection/inflammation was 28.3% (39/138); (2) four parameters were used to develop a noninvasive risk scoring system [i.e. cervical fetal fibronectin concentration (score 0-2), maternal serum CRP concentration (score 0-2), cervical dilatation (score 0-2), and gestational age at presentation (score 0-1)]; the total score ranges from 0 to 7; 3) the area under the curve of the risk score was 0.96 (95% confidence interval (CI), 0.92-0.99), significantly higher than that of each predictor in the identification of intra-amniotic infection/inflammation (p < .001, for all); 4) the risk score with a cutoff of 4 had a sensitivity of 94.9% (37/39), a specificity of 90.9% (90/99), a positive predictive value of 80.4% (37/46), a negative predictive value of 97.8% (90/92), a positive likelihood ratio of 10.4 (95% CI, 5.6-19.5), and a negative likelihood ratio of 0.06 (95% CI, 0.15-0.22) in the identification of intra-amniotic infection/inflammation.

CONCLUSIONS

(1) The combination of four parameters (concentrations of cervical fetal fibronectin and maternal serum CRP, cervical dilatation, and gestational age) was independently associated with intra-amniotic infection and/or inflammation; and (2) the risk scoring system comprised of the combination of 4 noninvasive parameters was sensitive and specific to identify the patients at risk for intra-amniotic infection and/or inflammation.

The web-based application "QUiPP v.2" for the prediction of preterm birth in symptomatic women is not yet ready for worldwide clinical use: ten reflections on development, validation and use

PURPOSE

In this correspondence, we highlight general and domain-specific caveats in the development and validation of prediction models.

METHODS

Development and use of the "QUiPP" application, a tool for preterm birth prediction which is supported by the United Kingdom National Health Service, is scrutinised and commented on.

RESULTS

We highlight and elaborate ten points which may be perceived to be unclear or potentially misleading.

CONCLUSION

While the QUiPP application has high potential, it lacks transparency (on certain aspects related to model development) and proper validation. This precludes transportability to settings with other treatment policies and to other countries where the app has been made publicly available.

Antenatal thymus volumes in fetuses that delivered <32 weeks' gestation: An MRI pilot study

INTRODUCTION

Infection and inflammation have been implicated in the etiology and subsequent morbidity associated with preterm birth. At present, there are no tests to assess for fetal compartment infection. The thymus, a gland integral in the fetal immune system, has been shown to involute in animal models of antenatal infection, but its response in human fetuses has not been studied. This study aims: (a) to generate magnetic resonance imaging (MRI) -derived fetal thymus volumes standardized for fetal weight; (b) to compare standardized thymus volumes from fetuses that delivered before 32 weeks of gestation with fetuses that subsequently deliver at term; (c) to assess thymus size as a predictor of preterm birth; and (d) to correlate the presence of chorioamnionitis and funisitis at delivery with thymic volumes in utero in fetuses that subsequently deliver preterm.

MATERIAL AND METHODS

Women at high-risk of preterm birth at 20-32 weeks of gestation were recruited. A control group was obtained from existing data sets acquired as part of three research studies. A fetal MRI was performed on a 1.5T or 3T MRI scanner: T2 weighted images were obtained of the entire uterine content and specifically the fetal thorax. A slice-to-volume registration method was used for reconstruction of three-dimensional images of the thorax. Thymus segmentations were performed manually. Body volumes were calculated by manual segmentation and thymus:body volume ratios were generated. Comparison of groups was performed using multiple regression analysis. Normal ranges were created for thymus volume and thymus:body volume ratios using the control data. Receiver operating curves (ROC) curves were generated for thymus:body volume ratio and gestation-adjusted thymus volume centiles as predictors of preterm birth. Placental histology was analyzed where available from pregnancies that delivered very preterm and the presence of chorioamnionitis/funisitis was noted.

RESULTS

Normative ranges were created for thymus volume, and thymus volume was standardized for fetal size from fetuses that subsequently delivered at term, but were imaged at 20-32 weeks of gestation. Image data sets from 16 women that delivered <32 weeks of gestation (ten with ruptured membranes and six with intact membranes) and 80 control women that delivered >37 weeks were included. Mean gestation at MRI of the study group was 28⁺⁴  weeks (SD 3.2) and for the control group was 25⁺⁵  weeks (SD 2.4). Both absolute fetal thymus volumes and thymus:body volume ratios were smaller in fetuses that delivered preterm (P < .001). Of the 16 fetuses that delivered preterm, 13 had placental histology, 11 had chorioamnionitis, and 9 had funisitis. The strongest predictors of prematurity were the thymus volume Z-score and thymus:body volume ratio Z-score (ROC areas 0.915 and 0.870, respectively).

CONCLUSIONS

We have produced MRI-derived normal ranges for fetal thymus and thymus:body volume ratios between 20 and 32 weeks of gestation. Fetuses that deliver very preterm had reduced thymus volumes when standardized for fetal size. A reduced thymus volume was also a predictor of spontaneous preterm delivery. Thymus volume may be a suitable marker of the fetal inflammatory response, although further work is needed to assess this, increasing the sample size to correlate the extent of chorioamnionitis with thymus size.

All the right moves: why in utero transfer is both important for the baby and difficult to achieve and new strategies for change

The best way to ensure that preterm infants benefit from relevant neonatal expertise as soon as they are born is to transfer the mother and baby to an appropriately specialised neonatal facility before birth (“ in utero”). This review explores the evidence surrounding the importance of being born in the right unit, the advantages of in utero transfers compared to ex utero transfers, and how to accurately assess which women are at most risk of delivering early and the challenges of in utero transfers.

Accurate identification of the women most at risk of preterm birth is key to prioritising who to transfer antenatally, but the administrative burden and pathway variation of in utero transfer in the UK are likely to compromise optimal clinical care. Women reported the impact that in utero transfers have on them, including the emotional and financial burdens of being transferred and the anxiety surrounding domestic and logistical concerns related to being away from home. The final section of the review explores new approaches to reforming the in utero transfer process, including learning from outside the UK and changing policy and guidelines. Examples of collaborative regional guidance include the recent Pan-London guidance on in utero transfers. Reforming the transfer process can also be aided through technology, such as utilising the CotFinder app.

In utero transfer is an unavoidable aspect of maternity and neonatal care, and the burden will increase if preterm birth rates continue to rise in association with increased rates of multiple pregnancy, advancing maternal age, assisted reproductive technologies, and obstetric interventions. As funding and capacity pressures on health services increase because of the COVID-19 pandemic, better prioritisation and sustained multi-disciplinary commitment are essential to maximise better outcomes for babies born too soon.

Commentary on a combined approach to the problem of developing biomarkers for the prediction of spontaneous preterm labor that leads to preterm birth

INTRODUCTION

Globally, preterm birth has replaced congenital malformation as the major cause of perinatal mortality and morbidity. The reduced rate of congenital malformation was not achieved through a single biophysical or biochemical marker at a specific gestational age, but rather through a combination of clinical, biophysical and biochemical markers at different gestational ages. Since the aetiology of spontaneous preterm birth is also multifactorial, it is unlikely that a single biomarker test, at a specific gestational age will emerge as the definitive predictive test.

METHODS

The Biomarkers Group of PREBIC, comprising clinicians, basic scientists and other experts in the field, with a particular interest in preterm birth have produced this commentary with short, medium and long-term aims: i) to alert clinicians to the advances that are being made in the prediction of spontaneous preterm birth; ii) to encourage clinicians and scientists to continue their efforts in this field, and not to be disheartened or nihilistic because of a perceived lack of progress and iii) to enable development of novel interventions that can reduce the mortality and morbidity associated with preterm birth.

RESULTS

Using language that we hope is clear to practising clinicians, we have identified 11 Sections in which there exists the potential, feasibility and capability of technologies for candidate biomarkers in the prediction of spontaneous preterm birth and how current limitations to this research might be circumvented.

DISCUSSION

The combination of biophysical, biochemical, immunological, microbiological, fetal cell, exosomal, or cell free RNA at different gestational ages, integrated as part of a multivariable predictor model may be necessary to advance our attempts to predict sPTL and PTB. This will require systems biological data using "omics" data and artificial intelligence/machine learning to manage the data appropriately. The ultimate goal is to reduce the mortality and morbidity associated with preterm birth.

Foetal lung volumes in pregnant women who deliver very preterm: a pilot study

BACKGROUND

Infants born preterm are at increased risk of pulmonary morbidity. The contribution of antenatal factors to impairments in lung structure/function has not been fully elucidated. This study aimed to compare standardized lung volumes from foetuses that were delivered <32 weeks' gestation with foetuses that were delivered >37 weeks.

METHODS

Fourteen women who delivered <32 weeks gestation and 56 women who delivered >37 underwent a foetal MRI. Slice-volume reconstruction was then used and the foetal lungs were then segmented using multi-atlas approaches. Body volumes were calculated by manual segmentation and lung:body volume ratios generated.

RESULTS

Mean gestation at MRI of the preterm group was 27⁺² weeks (SD 2.9, range 20⁺⁶-31⁺³) and control group 25⁺³ weeks (SD 4.7 range 20⁺⁵-31⁺⁶). Mean gestation at delivery of the preterm group was 29⁺² weeks (SD 2.6, range 22⁺⁰-32⁺⁰). Lung:body volume ratios and foetal lung volumes were smaller in foetuses that were delivered preterm both with and without preterm premature rupture of membranes compared to those born at term (p < 0.001 in all cases).

CONCLUSIONS

Foetuses that were delivered very preterm had reduced lung volumes when standardized for foetal size, irrespective of ruptured membranes. These are novel findings and suggest an antenatal aetiology of insult and possible focus for future preventative therapies.

Development and validation of predictive models for QUiPP App v.2: tool for predicting preterm birth in women with symptoms of threatened preterm labor

OBJECTIVE

To develop enhanced prediction models to update the QUiPP App prototype, a tool providing individualized risk of spontaneous preterm birth (sPTB), for use in women with symptoms of threatened preterm labor (TPTL), incorporating risk factors, transvaginal ultrasound assessment of cervical length (CL) and cervicovaginal fluid quantitative fetal fibronectin (qfFN) test results.

METHODS

Participants were pregnant women between 23 + 0 and 34 + 6 weeks' gestation with symptoms of TPTL, recruited as part of four prospective cohort studies carried out at 16 UK hospitals between October 2010 and October 2017. The training set comprised all women whose outcomes were known in May 2017 (n = 1032). The validation set comprised women whose outcomes were gathered between June 2017 and March 2018 (n = 506). Parametric survival models were developed for three combinations of predictors: risk factors plus qfFN test results alone, risk factors plus CL alone, and risk factors plus both qfFN and CL. The best models were selected using the Akaike and Bayesian information criteria. The estimated probability of sPTB < 30, < 34 or < 37 weeks' gestation and within 1 or 2 weeks of testing was calculated and receiver-operating-characteristics (ROC) curves were created to demonstrate the diagnostic ability of the prediction models.

RESULTS

Predictive statistics were similar between the training and the validation sets at most outcome time points and for each combination of predictors. Areas under the ROC curves (AUC) demonstrated that all three algorithms had good accuracy for the prediction of sPTB at < 30, < 34 and < 37 weeks' gestation and within 1 and 2 weeks' post-testing in the validation set, particularly the model combining risk factors plus qfFN alone (AUC: 0.96 at < 30 weeks; 0.85 at < 34 weeks; 0.77 at < 37 weeks; 0.91 at < 1 week from testing; and 0.92 at < 2 weeks from testing).

CONCLUSIONS

Validation of the new prediction models suggests that the QUiPP App v.2 can reliably calculate risk of sPTB in women with TPTL. Use of the QUiPP App in practice could lead to better targeting of intervention, while providing reassurance and avoiding unnecessary intervention in women at low risk. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

The use of specialised preterm birth clinics for women at high risk of spontaneous preterm birth: a systematic review

Background

Specialised preterm birth clinics care for women at high risk of spontaneous preterm birth. This systematic review assesses current practice within preterm birth clinics globally.

Methods

A comprehensive search strategy was used to identify all studies on preterm birth clinics on the MEDLINE, Embase, PsycINFO, CENTRAL and CINAHL databases. There were no restrictions to study design. Studies were limited to the English language and publications from 1998 onwards. Two reviewers assessed studies for inclusion, performed data extraction and reviewed methodological quality. Primary outcomes were referral criteria, investigations and interventions offered in preterm birth clinics. Secondary outcomes were the timing of planned first and last appointments and frequency of review.

Results

Thirty-two records fulfilled eligibility criteria and 20 studies were included in the main analysis following grouping of records describing the same study or clinic. Studies were of mixed study design and methodological quality. A total of 39 clinics were described; outcome data was not available for all clinics. Referral criteria included previous spontaneous preterm birth (38/38, 100%), previous mid-trimester loss (34/38, 89%) and previous cervical surgery (33/38, 87%). All clinics offered transvaginal cervical length scans. Additional investigations varied, including urogenital swabs (16/28, 57%) and fetal fibronectin (8/28, 29%). The primary treatment of choice for a sonographic short cervix was cervical cerclage in 10/33 (30%) clinics and vaginal progesterone in 6/33 (18%), with 10/33 (30%) using multiple first-line options and 6/33 (18%) using a combination of treatments. The majority of clinics planned timing of first review for 12–16 weeks (30/35, 86%) and the frequency of review was usually determined by clinical findings (18/24, 75%). There was a wide variation in gestational age at clinic discharge between 24 and 37 weeks.

Conclusions

There is variation in the referral criteria, investigations and interventions offered in preterm birth clinics and in the timing and frequency of review. Consistency in practice may improve with the introduction of consensus guidelines and national preterm birth prevention programmes.

Trial registration

Systematic review registration number: CRD42019131470.

The role of medical smartphone apps in clinical decision-support: A literature review

INTRODUCTION

The now ubiquitous smartphone has huge potential to assist clinical decision-making across the globe. However, the rapid pace of digitalisation contrasts starkly with the slower rate of medical research and publication. This review explores the evidence base that exists to validate and evaluate the use of medical decision-support apps. The resultant findings will inform appropriate and pragmatic evaluation strategies for future clinical app developers and provide a scientific and cultural context for research priorities in this field.

METHOD

Medline, Embase and Cochrane databases were searched for clinical trials concerning decision support and smart phones from 2007 (introduction of first smartphone iPhone) until January 2019.

RESULTS

Following exclusions, 48 trials and one Cochrane review were included for final analysis. Whilst diagnostic accuracy studies are plentiful, clinical trials are scarce. App research methodology was further interrogated according to setting and decision-support modality: e.g. camera-based, guideline-based, predictive models. Description of app development pathways and regulation were highly varied. Global health emerged as an early adopter of decision-support apps and this field is leading implementation and evaluation.

CONCLUSION

Clinical decision-support apps have considerable potential to enhance access to care and quality of care, but the medical community must rise to the challenge of modernising its approach if it is truly committed to capitalising on the opportunities of digitalisation.

Prevention and Therapy of Preterm Birth. Guideline of the DGGG, OEGGG and SGGG (S2k Level, AWMF Registry Number 015/025, February 2019) - Part 1 with Recommendations on the Epidemiology, Etiology, Prediction, Primary and Secondary Prevention of Preterm Birth

Aims This is an official guideline of the German Society for Gynecology and Obstetrics (DGGG), the Austrian Society for Gynecology and Obstetrics (ÖGGG) and the Swiss Society for Gynecology and Obstetrics (SGGG). The aim of this guideline is to improve the prediction, prevention and management of preterm birth based on evidence obtained from recent scientific literature, the experience of the members of the guideline commission and the views of self-help groups. Methods Based on the international literature, the members of the participating medical societies and organizations developed Recommendations and Statements. These were adopted following a formal process (structured consensus conference with neutral moderation, voting was done in writing using the Delphi method to achieve consensus). Recommendations Part I of this short version of the guideline lists Statements and Recommendations on the epidemiology, etiology, prediction and primary and secondary prevention of preterm birth.

Predictive value of cervical cytokine, antimicrobial and microflora levels for pre-term birth in high-risk women

Spontaneous preterm birth (sPTB, delivery <37 weeks gestation), accounts for approximately 10% of births worldwide; the aetiology is multifactorial with intra-amniotic infection being one contributing factor. This study aimed to determine whether asymptomatic women with a history of sPTB or cervical surgery have altered levels of inflammatory/antimicrobial mediators and/or microflora within cervical fluid at 22-24 weeks gestation. External cervical fluid was collected from women with history of previous sPTB and/or cervical surgery at 22-24 weeks gestation (n = 135). Cytokine and antimicrobial peptides were measured on a multiplex platform or by ELISA. qPCR was performed for detection of 7 potentially pathogenic bacterial species. IL-8 and IL-1β levels were lower in women who delivered preterm compared to those who delivered at term (IL-8 P = 0.02; IL-1β P = 0.04). There were no differences in elafin or human beta defensin-1 protein levels between the two groups. Multiple bacterial species were detected in a higher proportion of women who delivered preterm than in those who delivered at term (P = 0.005). Cervical fluid IL-8 and IL-1β and microflora have the potential to be used as biomarkers to predict sPTB in high risk women.

Reducing the impact of preterm birth: Preterm birth commissioning in the United Kingdom

Reducing preterm birth is a priority for Maternity and Children’s services. In the recent UK Department of Health publication ‘Safer Maternity Care’ the Secretary of State for Health aimed to achieve the national maternity safety ambition by pledging to reduce the rate of preterm birth from 8% to 6%. It was proposed that specialist preterm birth services should be established in the UK in order to achieve this aim. In response the Preterm Clinical Network has written Commissioning Guidance aimed to establish best practice pathways and agreed models of care to reduce variation nationally. They have been developed by clinical experts in the field, from within the UK, to provide recommendations for commissioning groups and to recommend pathways to organisations with the aim of reducing the incidence of preterm birth. Three key areas of care provision are focused on: prediction, prevention and preparation of women at high risk of PTB. This Expert Opinion, will summarise the Commissioning Guidance.

EQUIPTT: The Evaluation of the QUiPP app for Triage and Transfer protocol for a cluster randomised trial to evaluate the impact of the QUiPP app on inappropriate management for threatened preterm labour

Background

Accurate diagnosis of preterm labour is needed to ensure correct management of those most at risk of preterm birth and to prevent the maternal and fetal risks incurred by unnecessary interventions given to the large majority of women, who do not deliver within a week of presentation. Intervention “just-in-case” results in many avoidable admissions, women being transferred out of their local hospital unnecessarily and most women receiving unwarranted drugs, such as steroids and tocolytics. It also precludes appropriate transfers for others as neonatal cots are blocked pre-emptively, resulting in more dangerous ex-utero transfers. We have developed the QUiPP App which is a clinical decision-making aid based on previous outcomes of women, quantitative fetal fibronectin (qfFN) values and cervical length. It is hypothesised that using the QUiPP app will reduce inappropriate admissions and transfers.

Methods

A multi-site cluster randomised trial will evaluate whether the QUiPP app reduces inappropriate management for threatened preterm labour. The 13 participating centres will be randomly allocated to receive either intervention or control. If the QUiPP app calculates risk of delivery within 7 days to be is less than 5%, clinicians are advised that interventions may be withheld. Women’s experience of threatened preterm labour assessment will be explored using self-completed questionnaires, with a subset of participants being invited to semi-structured interview. A health economics analysis is also planned.

Discussion

We hypothesise that the QUiPP app will improve identification of the most appropriate women for admission and transfer and ensure that therapies known to reduce risk of preterm neonatal morbidities are offered to those who need them. We will determine which women do not require these therapies, thereby reducing over-medicalisation and the associated maternal and fetal risks for these women. The findings will inform future national guidelines on threatened preterm labour. Beyond obstetrics, evaluating the impact of an app in an emergency setting, and our emphasis on balancing harms of over-treatment as well as under-treatment, make EQUIPTT a valuable contribution to translational medicine.

Trial registration

The EQUIPTT trial was prospectively registered on 16th January 2018 with the ISRCTN registry (no. 17846337).

The fetal fibronectin test: 25 years after its development, what is the evidence regarding its clinical utility? A systematic review and meta-analysis

Background: The identification of women at risk for preterm birth should allow interventions which could improve neonatal outcome. Fetal fibronectin, a glycoprotein which acts normally as glue between decidua and amniotic membranes could be a good marker of impending labour when its concentration in cervicovaginal secretions between 22 and 36 weeks of gestation is ≥50 ng/mL. Many authors worldwide have tested this marker with many different methodologies and clinical settings, but conclusions about its clinical use are mixed. It is time for a comprehensive update through a systematic review and meta-analysis.Methods: We searched PubMed, Cochrane Library, and Embase, supplemented by manual search of bibliographies of known primary and review articles, international conference papers, and contact with experts from 1-1990 to 2-2018. We have selected all type of studies involving fetal fibronectin test accuracy for preterm delivery. Two authors independently extracted data about study characteristics and quality from identified publications. Contingency tables were constructed. Reference standards were preterm delivery before 37, 36, 35, 34, and 32 weeks, within 28, 21, 14, or 7 d and within 48 h. Data were pooled to produce summary likelihood ratios for positive and negative tests results.Results: One hundred and ninety-three primary studies were identified allowing analysis of 53 subgroups. In all settings, none of the summary likelihood ratios were >10 or <0.1, thus indicating moderate prediction, particularly in asymptomatic women and in multiple gestations.Conclusions: The fetal fibronectin test should not be used as a screening test for asymptomatic women. For high-risk asymptomatic women, and especially for women with multiple pregnancies, the performance of the fetal fibronectin test was also too low to be clinically relevant. Consensual use as a diagnostic tool for women with suspected preterm labor, the best use policy probably still depends on local contingencies, future cost-effectiveness analysis, and comparison with other more recent available biochemical markers.

Quantitative fetal fibronectin and cervical length in symptomatic women: results from a prospective blinded cohort study. J Matern Fetal Neonatal Med 2018;32:3792-3800. [PMID: 29727248 DOI: 10.1080/14767058.2018.1472227]

Objectives: Our objectives were to determine whether quantitative fetal fibronectin (fFN) and cervical length (CL) screening can be used alone or in combination as prognostic tests to identify symptomatic women at the highest or lowest risk for spontaneous preterm birth (sPTB). Methods: A prospective, blinded cohort study of women presenting with a singleton gestation to our triage unit between 22-33w6d with preterm labor symptoms was performed. Women with ruptured membranes, moderate/severe bleeding, and dilation >2 cm were excluded. The primary outcome was sPTB <37 weeks. We evaluated test characteristics of quantitative fFN and CL assessment, both separately and in combination, considering traditionally reported cut-points (fFN ≥50 and CL <25), as well as cut-points above and below these measures. We found interactions between fFN >50 and CL <25 and sPTB by parity and obstetric history (p < .05) and therefore stratified results. Test characteristics are presented with positive predictive value (PPV) and negative predictive value (NPV). Results: Five hundred eighty women were enrolled and 537 women were available for analysis. Overall sPTB rate was 11.1%. Among nulliparous women, increasing levels of fFN were associated with increasing risk of sPTB, with PPV going from 26.5% at ≥20 ng/mL to 44.4% at ≥200 ng/mL. A cut-point of 20 ng/mL had higher sensitivity (69.2%) and higher NPV (96.8%) and therefore identified a "low-risk" group. fFN was not informative for multiparous women regardless of prior obstetrical history or quantitative level chosen. For all women, a shorter CL was associated with an increased sPTB risk. Among nulliparas and multiparas without a prior sPTB, a CL <20 mm optimized test characteristics (PPV 25 and 20%, NPV 95.5, and 92.7%, respectively). For multiparas with a prior sPTB, CL <25 mm was more useful. Using fFN and CL in combination for nulliparas did not improve test characteristics over using the individual fFN (p = .74) and CL (p = .31) components separately. Conclusions: This study identifies the importance of stratifying by parity and obstetrical history when using screening modalities for risk assessment in symptomatic women. For nulliparous women, either quantitative fFN or cervical length assessment can be utilized, depending on resources available, but a lower cut-point of 20 ng/mL should be used for quantitative fFN. For multiparous women, fFN is not useful and cervical length assessment should be the main screening tool utilized when there is clinical uncertainty. Regardless of parity, the PPV of fFN and CL is low and therefore the greatest clinical utility remains in its NPV.

Predicting preterm birth: Cervical length and fetal fibronectin

Spontaneous preterm birth remains the leading cause of neonatal morbidity and mortality worldwide, and accounts for a significant global health burden. Several obstetric strategies to screen for spontaneous preterm delivery, such as cervical length and fetal fibronectin measurement, have emerged. However, the effectiveness of these strategies relies on their ability to accurately predict those pregnancies at increased risk for spontaneous preterm birth (SPTB). Transvaginal cervical shortening is predictive of preterm birth and when coupled with appropriate preterm birth prevention strategies, has been associated with reductions in SPTB in asymptomatic women with a singleton gestation. The use of qualitative fetal fibronectin may be useful in conjunction with cervical length assessment in women with acute preterm labor symptoms, but data supporting its clinical utility remain limited. As both cervical length and qualitative fetal fibronectin have limited capacity to predict preterm birth, further studies are needed to investigate other potential screening modalities.

The QUiPP App: a safe alternative to a treat-all strategy for threatened preterm labor

OBJECTIVE

To evaluate the impact of triaging women at risk of spontaneous preterm birth (sPTB) using the QUiPP App, which incorporates a predictive model combining history of sPTB, gestational age and quantitative measurements of fetal fibronectin, compared with a treat-all policy (advocated by the UK National Institute for Health and Care Excellence) among women with threatened preterm labor before 30 weeks' gestation.

METHODS

Prospectively collected data of pregnant women presenting with symptoms of preterm labor (abdominal pain or tightening) at 24-34 weeks' gestation were retrieved from the research databases of the EQUIPP and PETRA studies for subanalysis. Each episode of threatened preterm labor was retrospectively assigned a risk for sPTB within 7 days using the QUiPP App. A primary outcome of delivery within 7 days was used to model the performance accuracy of the QUiPP App compared with a treat-all policy.

RESULTS

Using a 5% risk of delivery within 7 days according to the QUiPP App as the threshold for intervention, 9/9 women who presented with threatened preterm labor < 34 weeks would have been treated correctly, giving a sensitivity of 100% (one-sided 97.5% CI, 66.4%) and a negative predictive value of 100% (97.5% CI, 98.9-100%). The positive predictive value for delivery within 7 days was 30.0% (95% CI, 11.9-54.3%) for women presenting before 30 weeks and 20.0% (95% CI, 12.7-30.1%) for women presenting between 30 + 0 and 34 + 0 weeks. If this 5% threshold had been used to triage women presenting between 24 + 0 and 29 + 6 weeks, 89.4% (n = 168) of admissions could have been safely avoided, compared with 0% for a treat-all strategy. No true case of preterm labor would have been missed, as no woman who was assigned a risk of < 10% delivered within 7 days.

CONCLUSION

For women with threatened preterm labor, the QUiPP App can accurately guide management at risk thresholds for sPTB of 1%, 5% and 10%, allowing outpatient management in the vast majority of cases. A treat-all approach would not have avoided admission for any woman, and would have exposed 188 mothers and their babies to unnecessary hospitalization and steroid administration and increased the burden on network and transport services owing to unnecessary in-utero transfers. Prediction of sPTB should be performed before 30 weeks to determine management until there is evidence that such a high level of unnecessary intervention, as suggested by the treat-all strategy, does less harm than the occurrence of rare false negatives. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Applying Precision Public Health to Prevent Preterm Birth

Preterm birth (PTB) is one of the major health-care challenges of our time. Being born too early is associated with major risks to the child with potential for serious consequences in terms of life-long disability and health-care costs. Discovering how to prevent PTB needs to be one of our greatest priorities. Recent advances have provided hope that a percentage of cases known to be related to risk factors may be amenable to prevention; but the majority of cases remain of unknown cause, and there is little chance of prevention. Applying the principle of precision public health may offer opportunities previously unavailable. Presented in this article are ideas that may improve our abilities in the fields of studying the effects of migration and of populations in transition, public health programs, tobacco control, routine measurement of length of the cervix in mid-pregnancy by ultrasound imaging, prevention of non-medically indicated late PTB, identification of pregnant women for whom treatment of vaginal infection may be of benefit, and screening by genetics and other “omics.” Opening new research in these fields, and viewing these clinical problems through a prism of precision public health, may produce benefits that will affect the lives of large numbers of people.

Inflammasome activators induce fibronectin expression and release in macrophages

Extracellular fibronectin (Fn) can activate pro-inflammatory pathways and serves as an endogenous danger signalling molecule; thus, it has been suggested as a biomarker for several diseases. In the present study, we found that pathogen-derived activators of the inflammasomes induce the expression and secretion of Fn in macrophages through a mechanism involving adenosine triphosphate and caspase-1 activation. We also found that plasma Fn induces caspase-1 activation and cell death in macrophages, epithelial cells, and fibroblasts. Together, these results indicate that Fn plays a critical role in inflammasome-activated cells by amplifying caspase-1 activation and inducing inflammatory cell death.

Ability of a preterm surveillance clinic to triage risk of preterm birth: a prospective cohort study

OBJECTIVE

To identify whether preterm surveillance clinics (PSCs) risk-stratify high-risk women accurately by comparing outcomes of those admitted to hospital on the basis of asymptomatic testing with those not admitted.

METHODS

We performed a subanalysis from a larger prospective cohort study on sonographic cervical length, quantitative fetal fibronectin (qfFN) and risk of spontaneous preterm birth. We identified 1130 asymptomatic singleton pregnancies at high risk of preterm birth, screened between 23 and 28 weeks of gestation at a PSC in a tertiary hospital in London, UK. Gestational age at delivery, the proportion of preterm births that delivered < 30 weeks and neonatal outcomes were compared between women admitted electively when asymptomatic as a consequence of screening-test results and those who were not routinely admitted.

RESULTS

In total, 66 (6%) women attending the PSC were admitted to hospital following asymptomatic screening (inpatient group). The mean gestational age at delivery for those not admitted electively (outpatient group) was at term and was significantly higher than that of those admitted from PSC (38.4 vs 31.2 weeks; P < 0.0001). Preterm birth < 30 weeks' gestation was rare in the outpatient group relative to those admitted (1.32% vs 36.4%; P < 0.0001). Neonatal mortality was 0.188% in the outpatient group compared with 4.55% in those admitted electively (P < 0.0001). The incidence of other complications such as neonatal death, 5-min Apgar score < 7, special care baby unit/neonatal intensive care unit admission, respiratory distress syndrome, intraventricular hemorrhage and low birth weight were significantly lower in those managed as outpatients than in those admitted electively.

CONCLUSION

PSCs measuring cervical length and qfFN accurately triage asymptomatic high-risk pregnant women, enabling those at highest risk of adverse outcome to be identified for elective admission to hospital and appropriate management. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.