Cervicovaginal fibronectin improves the prediction of preterm delivery based on sonographic cervical length in patients with preterm uterine contractions and intact membranes

Knowledge mapping for prediction of spontaneous preterm birth

INTRODUCTION

Preterm birth (PTB) before 37 weeks gestation, especially spontaneous premature birth (sPTB), poses significant global health challenges, with rising rates linked to advanced and multiple pregnancies. Despite efforts to understand the pathogenesis and related biomarkers of sPTB, accurate prediction is still difficult to achieve. Recent research in academic journals has focused on sPTB prediction, prompting our bibliometric analysis to understand the current situation and explore the new research direction.

METHODS

We used keywords in the Web of Science Core Collection (WoSCC) to search for articles related to sPTB prediction from 2004 to 2023. Subsequently, we primarily employed three distinct software tools (VOSviewer, CiteSpace, and Python) for conducting this bibliometric analysis.

RESULTS

Focusing on sPTB as the primary subject, a total of 647 papers have been published in 136 academic journals. There are the most publications from The United States (n = 245, 39.26 %), and the University of London contributed the most publications (n = 57, 8.81 %). The American Journal of Obstetrics and Gynecology is the most productive academic journal on sPTB prediction [n = 74, 11.44 %; impact factor (IF) = 8.7]. Through the co-occurrence and cluster analysis, we found that recent research has focused on is "pamg-1", "uterocervical angle", "twin pregnancy", "quantitative ultrasound", and "lactobacillus iners".

CONCLUSION

We utilized bibliometric software to perform a comprehensive analysis of the literature concerning sPTB prediction. Broadly, the primary focus of future sPTB prediction lies in the application of novel ultrasound and biological markers, as well as in predicting sPTB in twin pregnancies.

Predictive Value of the sFlt-1/PlGF Ratio and Interleukin-6 for the Presence of Placental Lesions in Spontaneous Preterm Labor with Intact Membranes with Delivery within 7 Days

INTRODUCTION

The aim of the study was to identify predictive values of the soluble fms-like tyrosine kinase/placental growth factor (sFlt-1/PlGF) ratio and interleukin (IL)-6, assessed with a clinically available method in a large-volume biochemistry laboratory, in maternal blood, amniotic fluid, and umbilical cord blood for the presence of the placental lesions consistent with maternal vascular malperfusion (MVM) and acute histological chorioamnionitis (HCA), respectively.

METHODS

This retrospective study included 92 women with preterm labor with intact membranes (PTL) delivered within 7 days of admission with gestational ages between 22+0 and 34+6 weeks. The sFlt-1/PlGF ratio and IL-6 were assessed in stored samples of maternal serum, amniotic fluid, and umbilical cord serum using Elecsys® sFlt-1, PlGF, and IL-6 immunoassays.

RESULTS

Women with MVM had a higher sFlt-1/PlGF ratio in the maternal serum, compared to those without MVM (19.9 vs. 4.6; p < 0.0001), but not in the amniotic fluid or umbilical cord blood. A cut-off value of 8 for the sFlt-1/PlGF ratio in maternal serum was identified as optimal for predicting MVM in patients with PTL. Women with HCA had higher concentrations of IL-6 in maternal serum, compared to those without HCA (11.1 pg/mL vs. 8.4 pg/mL; p = 0.03), amniotic fluid (9,216 pg/mL vs. 1,423 pg/mL; p < 0.0001), and umbilical cord blood (20.7 pg/mL vs. 10.7 pg/mL, p = 0.002). Amniotic-fluid IL-6 showed the highest predictive value. A cut-off value of IL-6 concentration in the amniotic fluid of 5,000 pg/mL was found to be optimal for predicting HCA in PTL.

CONCLUSION

Maternal serum sFlt-1/PlGF and amniotic fluid IL-6 concentrations can be used for liquid biopsy to predict placental lesions in women with PTL who deliver within 7 days.

Clinical application of amino-terminal pro-brain natriuretic peptide concentration in amniotic fluid for the prediction of preterm birth in symptomatic women

BACKGROUND

Preterm birth accounts for 60% to 80% of neonatal mortality. Approximately one-third of preterm births are caused by the spontaneous onset of preterm labor. Nevertheless, 70% to 90% of women diagnosed with preterm labor will not deliver within 7 days. Thus, many women will be unnecessarily treated by preterm labor with risk medications. Better tools are needed to categorize women in preterm labor into high or low risk of preterm delivery.

OBJECTIVE

This study aimed to evaluate the amino-terminal pro-brain natriuretic peptide concentration in the amniotic fluid as a prognostic test to predict the risk of delivery within 48 hours or 7 days and before 34 0/7 or 37 0/7 weeks of gestation in women in preterm labor.

STUDY DESIGN

A total of 102 pregnant women presenting signs and symptoms of spontaneous preterm birth (22 0/7 to 34 0/7 weeks of gestation) were included. Amniotic fluid was obtained by amniocentesis, and amino-terminal pro-brain natriuretic peptide concentration was measured. Below normal concentration was defined as <0.5 multiples of the median of the standard curve according to gestational age. The risk of preterm delivery was estimated according to normal or lower-than-normal amino-terminal pro-brain natriuretic peptide concentrations. The predictive capacity of the test (below normal amino-terminal pro-brain natriuretic peptide concentration) was evaluated to identify spontaneous preterm birth at 48 hours or 7 days from amniocentesis and less than 34 0/7 or 37 0/7 weeks at delivery.

RESULTS

For the outcome delivery within 48 hours, lower-than-normal amino-terminal pro-brain natriuretic peptide concentration had 94.6% sensitivity, 73.8% specificity, 96.0% negative predictive value, 3.61 positive likelihood ratio, and 0.07 negative likelihood ratio. For the outcome delivery within 7 days, the test had 93.9% sensitivity, 88.7% specificity, 94.0% negative predictive value, 8.31 positive likelihood ratio, and 0.07 negative likelihood ratio. For the outcomes of spontaneous preterm birth before 34 0/7 and 37 0/7 weeks of gestation, below normal amino-terminal pro-brain natriuretic peptide concentrations had 80.0% sensitivity, 83.0% specificity, 78.0% negative predictive value, 4.70 positive likelihood ratio, and 0.24 negative likelihood ratio and 64.1% sensitivity, 91.7% specificity, 44.0% negative predictive value, 7.70 positive likelihood ratio, and 0.39 negative likelihood ratio, respectively.

CONCLUSION

Among patients in spontaneous preterm labor, the detection of lower-than-normal amino-terminal pro-brain natriuretic peptide concentrations (<0.5 multiples of the median) in amniotic fluid has an excellent predictive capacity to identify those patients at low risk of preterm delivery within 48 hours or 7 days.

Development and validation of a simplified risk prediction model for preterm birth: a prospective cohort study in rural Ethiopia

Preterm birth is one of the most common obstetric complications in low- and middle-income countries, where access to advanced diagnostic tests and imaging is limited. Therefore, we developed and validated a simplified risk prediction tool to predict preterm birth based on easily applicable and routinely collected characteristics of pregnant women in the primary care setting. We used a logistic regression model to develop a model based on the data collected from 481 pregnant women. Model accuracy was evaluated through discrimination (measured by the area under the Receiver Operating Characteristic curve; AUC) and calibration (via calibration graphs and the Hosmer-Lemeshow goodness of fit test). Internal validation was performed using a bootstrapping technique. A simplified risk score was developed, and the cut-off point was determined using the "Youden index" to classify pregnant women into high or low risk for preterm birth. The incidence of preterm birth was 19.5% (95% CI:16.2, 23.3) of pregnancies. The final prediction model incorporated mid-upper arm circumference, gravidity, history of abortion, antenatal care, comorbidity, intimate partner violence, and anemia as predictors of preeclampsia. The AUC of the model was 0.687 (95% CI: 0.62, 0.75). The calibration plot demonstrated a good calibration with a p-value of 0.713 for the Hosmer-Lemeshow goodness of fit test. The model can identify pregnant women at high risk of preterm birth. It is applicable in daily clinical practice and could contribute to the improvement of the health of women and newborns in primary care settings with limited resources. Healthcare providers in rural areas could use this prediction model to improve clinical decision-making and reduce obstetrics complications.

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.

Society for Maternal-Fetal Medicine Special Statement: Quality metrics for optimal timing of antenatal corticosteroid administration

Preterm birth is a leading cause of perinatal morbidity and mortality. Antenatal corticosteroid administration before preterm birth reduces the risks of perinatal death, respiratory morbidity, necrotizing enterocolitis, and intraventricular hemorrhage and reduces the costs of perinatal care. Antenatal corticosteroids are optimally effective when administered within 7 days before preterm birth. However, only 20% to 40% of early preterm infants receive antenatal corticosteroids within 7 days before birth, in part because it is difficult to predict the precise timing of preterm birth. Until 2020, The Joint Commission had a Perinatal Care quality metric measuring the rate of antenatal corticosteroid administration at any time before early preterm birth. This metric incentivized providers to use antenatal corticosteroids liberally. The Joint Commission retired the metric in 2020 after the rate reached more than 97% in The Joint Commission-accredited hospitals. However, the metric did not evaluate whether the timing of antenatal corticosteroid administration was optimal, that is, within 7 days of birth. A 2016 multistakeholder Cooperative Workshop recommended the development of a new quality metric to assess the rate of optimally timed antenatal corticosteroids among early preterm births. In this statement, we outline proposed specifications for such a metric and discuss potential uses, advantages, limitations, and barriers. Furthermore, we propose a balancing metric that tracks the percentage of patients treated with antenatal corticosteroids who ultimately give birth at term. We suggest that the use of these new metrics may incentivize more conservative antenatal corticosteroid timing, which could, in turn, lead to meaningfully improved outcomes for preterm neonates.

Society for Maternal-Fetal Medicine Special Statement: Cognitive bias and medical error in obstetrics-challenges and opportunities

The processes of diagnosis and management involve clinical decision-making. However, decision-making is often affected by cognitive biases that can lead to medical errors. This statement presents a framework of clinical thinking and decision-making and shows how these processes can be bias-prone. We review examples of cognitive bias in obstetrics and introduce debiasing tools and strategies. When an adverse event or near miss is reviewed, the concept of a cognitive autopsy-a root cause analysis of medical decision-making and the potential influence of cognitive biases-is promoted as part of the review process. Finally, areas for future research on cognitive bias in obstetrics are suggested.

A Timely Administration of Antenatal Steroids Is Highly Protective Against Intraventricular Hemorrhage: An Observational Multicenter Cohort Study of Very Low Birth Weight Infants

AIM

The aim of the study is to evaluate the influence of the timing of antenatal steroids (ANSs) on neonatal outcome of very low birth weight infants (VLBWI) born before 30 weeks of gestation in the German Neonatal Network.

METHODS

The German Neonatal Network is a large population-based cohort study enrolling VLBWIs since 2009. We included 672 neonates, who were born between January 1, 2009 and December 31, 2019 in our analysis in 10 selected centers. Infants were divided into four subgroups based on the interval between the first steroid administration and preterm birth: (I) two doses of betamethasone, ANS-birth interval: >24 h to 7 days, n = 187, (II) only one dose of betamethasone, ANS-birth interval 0-24 h, n = 70, (III) two doses of betamethasone, ANS-birth interval >7 days, n = 177, and (IV) no antenatal steroids, n = 238. Descriptive statistics and logistic regression analyses were performed for the main neonatal outcome parameters. Group IV (no ANS) was used as a reference.

RESULTS

An ANS-birth interval of 24 h to 7 days after the first dose was associated with a reduced risk for intraventricular hemorrhage (OR 0.17; 95% CI 0.09-0.31, p < 0.001) and mechanical ventilation (OR 0.37; 95% CI 0.23-0.61, p < 0.001), whereas the group of infants that only received a single dose of steroids reflected a subgroup at high risk for adverse neonatal outcomes; an ANS-birth interval of >7 days was still associated with a lower risk for intraventricular hemorrhage (OR 0.43; 95% CI 0.25-0.72, p = 0.002) and the need for mechanical ventilation (OR 0.43; 95% CI 0.27-0.71, p = 0.001).

CONCLUSION

Our observational data indicate that an ANS-birth interval of 24 h to 7 days is strongly associated with a reduced risk of intraventricular hemorrhage in VLBWIs. Further research is needed to improve the prediction of preterm birth in order to achieve a timely administration of antenatal steroids that may improve neonatal outcomes such as intraventricular hemorrhage.

The use of PAMG-1 testing in patients with preterm labor, intact membranes and a short sonographic cervix reduces the rate of unnecessary antenatal glucocorticoid administration

OBJECTIVES

To assess the frequency of antenatal corticosteroid (ACS) administration in cases with shortened cervical length by addition of placental alpha-microglobulin-1 (PAMG-1) testing to sonographic examination.

METHODS

Single centre retrospective cohort study. Rate of ACS administration was compared between cases with cervical length between 15 and 25 mm and cases with positive PAMG-1 testing and cervical length between 15 and 25 mm. We evaluated the following outcome parameters: Rate of ACS administration, gestational age at delivery, time to delivery, delivery within seven days, delivery <34 and <37 weeks' gestation, rate of admission to neonatal intensive care unit (NICU).

RESULTS

In total, 130 cases were included. "PAMG-1 group" consisted of 68 women, 62 cases built the "historical control group". ACS administration was performed less frequently in the "PAMG-1 cohort" (18 (26%) vs. 46 (74%); p<0.001). The rate of delivery within seven days did not differ (2 (3%) vs. 4 (6.5%); p=0.4239). The rates of delivery <34 weeks' gestation (7 (10%) vs. 9 (15%); p=0.4643) and <37 weeks' gestation (19 (28%) vs. 26 (42%); p=0.0939) did not differ. Time to delivery interval was longer in the PAMG-1 group (61.5 vs. 43 days, p=0.0117). NICU admission occurred more often in the "historical control group" (22 (38%) vs. 28 (60%); p=0.0272).

CONCLUSIONS

Addition of biomarker testing can help to avoid unnecessary ACS administrations in women with shortened cervical length.

A prognostic model, including quantitative fetal fibronectin, to predict preterm labour: the QUIDS meta-analysis and prospective cohort study

BACKGROUND

The diagnosis of preterm labour is challenging. False-positive diagnoses are common and result in unnecessary, potentially harmful treatments (e.g. tocolytics, antenatal corticosteroids and magnesium sulphate) and costly hospital admissions. Measurement of fetal fibronectin in vaginal fluid is a biochemical test that can indicate impending preterm birth.

OBJECTIVES

To develop an externally validated prognostic model using quantitative fetal fibronectin concentration, in combination with clinical risk factors, for the prediction of spontaneous preterm birth and to assess its cost-effectiveness.

DESIGN

The study comprised (1) a qualitative study to establish the decisional needs of pregnant women and their caregivers, (2) an individual participant data meta-analysis of existing studies to develop a prognostic model for spontaneous preterm birth within 7 days in women with symptoms of preterm labour based on quantitative fetal fibronectin and clinical risk factors, (3) external validation of the prognostic model in a prospective cohort study across 26 UK centres, (4) a model-based economic evaluation comparing the prognostic model with qualitative fetal fibronectin, and quantitative fetal fibronectin with cervical length measurement, in terms of cost per QALY gained and (5) a qualitative assessment of the acceptability of quantitative fetal fibronectin.

DATA SOURCES/SETTING

The model was developed using data from five European prospective cohort studies of quantitative fetal fibronectin. The UK prospective cohort study was carried out across 26 UK centres.

PARTICIPANTS

Pregnant women at 22⁺⁰-34⁺⁶ weeks' gestation with signs and symptoms of preterm labour.

HEALTH TECHNOLOGY BEING ASSESSED

Quantitative fetal fibronectin.

MAIN OUTCOME MEASURES

Spontaneous preterm birth within 7 days.

RESULTS

The individual participant data meta-analysis included 1783 women and 139 events of spontaneous preterm birth within 7 days (event rate 7.8%). The prognostic model that was developed included quantitative fetal fibronectin, smoking, ethnicity, nulliparity and multiple pregnancy. The model was externally validated in a cohort of 2837 women, with 83 events of spontaneous preterm birth within 7 days (event rate 2.93%), an area under the curve of 0.89 (95% confidence interval 0.84 to 0.93), a calibration slope of 1.22 and a Nagelkerke R ² of 0.34. The economic analysis found that the prognostic model was cost-effective compared with using qualitative fetal fibronectin at a threshold for hospital admission and treatment of ≥ 2% risk of preterm birth within 7 days.

LIMITATIONS

The outcome proportion (spontaneous preterm birth within 7 days of test) was 2.9% in the validation study. This is in line with other studies, but having slightly fewer than 100 events is a limitation in model validation.

CONCLUSIONS

A prognostic model that included quantitative fetal fibronectin and clinical risk factors showed excellent performance in the prediction of spontaneous preterm birth within 7 days of test, was cost-effective and can be used to inform a decision support tool to help guide management decisions for women with threatened preterm labour.

FUTURE WORK

The prognostic model will be embedded in electronic maternity records and a mobile telephone application, enabling ongoing data collection for further refinement and validation of the model.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015027590 and Current Controlled Trials ISRCTN41598423.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 52. See the NIHR Journals Library website for further project information.

Value of cervical electrical impedance spectroscopy to predict spontaneous preterm delivery in asymptomatic women: the ECCLIPPx prospective cohort study

OBJECTIVES

Preterm birth (PTB) accounts for two-thirds of deaths of structurally normal babies and is associated with substantial lifetime healthcare costs. Prevention of PTB remains limited by the modest accuracy of prediction methods, namely transvaginal ultrasound (TVS) cervical length (CL) measurement and quantitative cervicovaginal fetal fibronectin (FFN) estimation. We report the first substantive study detailing the predictive performance of a cervical probe device based on electrical impedance spectroscopy (EIS) for PTB - the EleCtriCaL Impedance Prediction of Preterm birth by spectroscopy of the cervix (ECCLIPPx) study. We aimed to compare the accuracy of cervical EIS-based prediction of spontaneous PTB with that of prediction using TVS-CL and FFN in asymptomatic women in the mid-trimester.

METHODS

We studied asymptomatic women with a singleton pregnancy at 20-22 weeks' and 26-28 weeks' gestation. EIS was performed using a Sheffield Mark 5.0 device that makes measurements in the frequency range 76 Hz to 625 kHz using a small probe housing tetrapolar electrodes. TVS-CL and FFN were also measured. The associations of cervical EIS, TVS-CL and FFN with spontaneous delivery before 37 weeks and before 32 weeks were determined by multivariate linear and non-linear logistic regression analysis. Areas under the receiver-operating-characteristics curves (AUC) plots of sensitivity against specificity were used to compare the predictive performance of all parameters, both in isolation and in combination.

RESULTS

Of the 365 asymptomatic women studied at 20-22 weeks who were not receiving treatment, 29 had spontaneous PTB, 14 had indicated PTB and 322 had term birth. At the higher frequencies assessed, cervical EIS predicted spontaneous PTB before 37 weeks with an AUC of 0.76 (95% CI, 0.71-0.81), compared with AUCs of 0.72 (95% CI, 0.66-0.76) for TVS-CL and 0.62 (95% CI, 0.56-0.72) for FFN. Combining all three assessments improved the prediction of spontaneous PTB before 37 weeks (AUC, 0.79 (95% CI, 0.74-0.83)) compared with TVS-CL and FFN alone. Incorporating a history of spontaneous PTB (defined as previous mid-trimester miscarriage or spontaneous PTB (14 to < 37 weeks)) into the cervical EIS prediction model improved the accuracy of prediction of spontaneous PTB before 37 weeks (AUC, 0.83 (95% CI, 0.78-0.87)) and before 32 weeks (AUC, 0.86 (95% CI, 0.82-0.90)).

CONCLUSIONS

Mid-trimester cervical EIS assessment predicts spontaneous PTB. Larger confirmatory studies investigating its potential clinical utility and to inform effective preventive interventions are required. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Development and validation of a risk prediction model of preterm birth for women with preterm labour symptoms (the QUIDS study): A prospective cohort study and individual participant data meta-analysis

BACKGROUND

Timely interventions in women presenting with preterm labour can substantially improve health outcomes for preterm babies. However, establishing such a diagnosis is very challenging, as signs and symptoms of preterm labour are common and can be nonspecific. We aimed to develop and externally validate a risk prediction model using concentration of vaginal fluid fetal fibronectin (quantitative fFN), in combination with clinical risk factors, for the prediction of spontaneous preterm birth and assessed its cost-effectiveness.

METHODS AND FINDINGS

Pregnant women included in the analyses were 22+0 to 34+6 weeks gestation with signs and symptoms of preterm labour. The primary outcome was spontaneous preterm birth within 7 days of quantitative fFN test. The risk prediction model was developed and internally validated in an individual participant data (IPD) meta-analysis of 5 European prospective cohort studies (2009 to 2016; 1,783 women; mean age 29.7 years; median BMI 24.8 kg/m2; 67.6% White; 11.7% smokers; 51.8% nulliparous; 10.4% with multiple pregnancy; 139 [7.8%] with spontaneous preterm birth within 7 days). The model was then externally validated in a prospective cohort study in 26 United Kingdom centres (2016 to 2018; 2,924 women; mean age 28.2 years; median BMI 25.4 kg/m2; 88.2% White; 21% smokers; 35.2% nulliparous; 3.5% with multiple pregnancy; 85 [2.9%] with spontaneous preterm birth within 7 days). The developed risk prediction model for spontaneous preterm birth within 7 days included quantitative fFN, current smoking, not White ethnicity, nulliparity, and multiple pregnancy. After internal validation, the optimism adjusted area under the curve was 0.89 (95% CI 0.86 to 0.92), and the optimism adjusted Nagelkerke R2 was 35% (95% CI 33% to 37%). On external validation in the prospective UK cohort population, the area under the curve was 0.89 (95% CI 0.84 to 0.94), and Nagelkerke R2 of 36% (95% CI: 34% to 38%). Recalibration of the model's intercept was required to ensure overall calibration-in-the-large. A calibration curve suggested close agreement between predicted and observed risks in the range of predictions 0% to 10%, but some miscalibration (underprediction) at higher risks (slope 1.24 (95% CI 1.23 to 1.26)). Despite any miscalibration, the net benefit of the model was higher than "treat all" or "treat none" strategies for thresholds up to about 15% risk. The economic analysis found the prognostic model was cost effective, compared to using qualitative fFN, at a threshold for hospital admission and treatment of ≥2% risk of preterm birth within 7 days. Study limitations include the limited number of participants who are not White and levels of missing data for certain variables in the development dataset.

CONCLUSIONS

In this study, we found that a risk prediction model including vaginal fFN concentration and clinical risk factors showed promising performance in the prediction of spontaneous preterm birth within 7 days of test and has potential to inform management decisions for women with threatened preterm labour. Further evaluation of the risk prediction model in clinical practice is required to determine whether the risk prediction model improves clinical outcomes if used in practice.

TRIAL REGISTRATION

The study was approved by the West of Scotland Research Ethics Committee (16/WS/0068). The study was registered with ISRCTN Registry (ISRCTN 41598423) and NIHR Portfolio (CPMS: 31277).

A Question of Timing: 10-year Retrospective Analysis on the Use of Antenatal Steroids for Imminent Preterm Birth

OBJECTIVE

Antenatal steroids improve the neonatal outcome if they are administered within a therapeutic window of seven days before preterm birth. The aim of this study was to evaluate the timing of antenatal steroids for imminent preterm birth at a single center in Germany.

MATERIAL AND METHODS

A 10-year retrospective analysis of 843 preterm births between 24/0 and 33/6 weeks was performed from January 2008 to December 2017 at a German university hospital. We evaluated the timing of antenatal steroids according to the indication for their application. Descriptive statistics and binomial regression were performed to analyze factors influencing the timing of antenatal steroid administration.

RESULTS

Of 843 preterm births below 34 weeks included in our study, 752 pregnant women received antenatal steroids (89.2%). Only 301/843 women (35.7%) gave birth within the optimal window of 7 days after antenatal steroids. 91/843 women (10.8%) did not receive steroids. 130/843 women (15.4%) only received one dose, 76/843 (9.0%) gave birth within 8 to 14 days, and 245/843 (29.1%) more than 14 days later. In a binomial regression model, preterm premature rupture of membranes (OR 3.40, 95% CI 1.81 to 6.39, p<0.001), fetal growth restriction (OR 3.27, 95% CI 1.63 to 6.58, p=0.001), and preeclampsia (OR 2.83, 95% CI 1.37 to 5.83, p=0.005) were positively associated with optimal timing.

CONCLUSION

Two thirds of women with preterm birth before 34 weeks received antenatal steroids outside the optimal therapeutic window. Further research is needed to achieve an optimal effect of antenatal steroids on neonatal outcome and to reduce untimely as well as unnecessary interventions.

Is real-time dynamic cervical shortening predictive of preterm birth?- A case control study

OBJECTIVES

We aimed to assess the risk of preterm birth in those with real-time dynamic cervical shortening.

METHODS

A retrospective matched case-control study. The study group comprised all women with dynamic cervical shortening (≥4 mm) noted from 24 to 34 weeks of gestation during 2010-2017 at a university hospital. Two control groups of women were established by matching the minimal and maximal cervical length measured, as well as age, parity, gestational age, history of spontaneous preterm birth, symptoms of preterm labor, and delivery year.

RESULTS

Data from 339 women were analyzed, 113 with dynamic cervical shortening comprised the study group, and two groups with 113 women each, matched for the minimal and maximal cervical lengths measured comprised the control groups. Rates of spontaneous preterm birth rate at <37 weeks (32.7% vs. 15.9%; OR [95% CI]: 2.60 (1.36, 4.87), p = .004) and <35 weeks (15.9% vs. 5.3%; OR [95% CI]: 3.38 (1.29, 8.86), p = .013) were significantly higher among those with dynamic cervix than among the control group matched for the maximal cervical length, and comparable to the control group matched for the minimal cervical length. The negative predictive values of cervical length for preterm birth occurrence at various cutoff values were lower in those with dynamic cervix.

CONCLUSIONS

The minimal cervical length measured should be used to guide patient management when dynamic cervix is noted. In the setting of dynamic cervical change, the value of cervical length as a negative predictor of preterm birth is limited.

The utility of fetal fibronectin in asymptomatic singleton and twin pregnancies with a cervical length ≤ 10 mm

Objective: To examine the utility of fetal fibronectin (fFN) for predicting spontaneous preterm birth (PTB) in asymptomatic women with a cervical length (CL) ≤10 mm compared to those with a CL 11-25 mm.Methods: Data was collected on all women with nonanomalous singleton and twin gestations who underwent transvaginal CL at a single institution between 2009 and 2012. Women with an incidental short cervix (CL ≤ 25 mm) between 22 and 32 weeks who had an fFN result within 7 days thereafter were included. Indicated preterm deliveries at <14 days of fFN, women who underwent cerclage placement, and terminations of pregnancy were excluded. The primary outcome was spontaneous PTB within 7 and 14 days of the fFN. Sensitivity, specificity, and positive (PPV) and negative predictive value (NPV) of fFN for a CL ≤ 10 mm was calculated for singletons and twins and compared to those with a CL 11-25 mm.Results: Of the 213 women included, 117 (54.9%) were singletons and 96 (45%) were twins. Baseline characteristics were similar between those with a CL ≤ 10 mm and with a CL 11-25 mm in both singletons and twins. The NPV of fFN for delivery within 7 days in singletons and twins with a CL ≤ 10 mm was 100%, similar to those with a CL 11-25 mm (93-100%). The NPV of fFN for delivery within 14 days in singletons and twins with a CL ≤ 10 mm remained high (87.5-100%) when compared to those with a CL 11-25 mm (93-100%). The PPV of fFN for delivery within 7 and 14 days in both singletons and twins with a CL ≤ 10 mm was low (10-25%) and similar to those with a CL 11-25 mm (7.1-24.4%).Conclusions: The NPV of fFN in asymptomatic singleton and twin pregnancies with a CL ≤ 10 mm is high and comparable to the NPV of fFN in women with a longer CL. Routine fFN collection in this select population should be considered as it may avoid unnecessary and costly admissions, as well as assist with timing of antenatal corticosteroids.

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 Clinical Usefulness of Predictive Models for Preterm Birth with Potential Benefits: A KOrean Preterm collaboratE Network (KOPEN) Registry-Linked Data-Based Cohort Study

Background: Preterm birth is strongly associated with increasing mortality, incidence of disability, intensity of neonatal care required, and consequent costs. We examined the clinical utility of the potential preterm birth risk factors from admitted pregnant women with symptomatic preterm labor and developed prediction models to obtain information for prolonging pregnancies. Methods: This retrospective study included pregnant women registered with the KOrean Preterm collaboratE Network (KOPEN) who had symptomatic preterm labor, between 16 and 34 gestational weeks, in a tertiary care center from March to November 2016. Demographics, obstetric and medical histories, and basic laboratory test results obtained at admission were evaluated. The preterm birth probability was assessed using a nomogram and decision tree according to birth gestational age: early preterm, before 32 weeks; late preterm, between 32 and 37 weeks; and term, after 37 weeks. Results: Of 879 registered pregnant women, 727 who gave birth at a designated institute were analyzed. The rates of early preterm, late preterm, and term births were 18.16%, 44.02%, and 37.83%, respectively. With the developed nomogram, the concordance index for early and late preterm births was 0.824 (95% CI: 0.785-0.864) and 0.717 (95% CI: 0.675-0.759) respectively. Preterm birth was significantly more likely among women with multiple pregnancy and had water leakage due to premature rupture of membrane. The prediction rate for preterm birth based on decision tree analysis was 86.9% for early preterm and 73.9% for late preterm; the most important nodes are watery leakage for early preterm birth and multiple pregnancy for late preterm birth. Conclusion: This study aims to develop an individual overall probability of preterm birth based on specific risk factors at critical gestational times of preterm birth using a range of clinical variables recorded at the initial hospital admission. Therefore, these models may be useful for clinicians and patients in clinical decision-making and for hospitalization or lifestyle coaching in an outpatient setting.

Association of amniotic fluid sludge with preterm labor and histologic chorioamnionitis in pregnant Japanese women with intact membranes: A retrospective study

AIM

The presence of amniotic fluid sludge has been identified as a risk factor for preterm birth. We sought to validate the clinical characteristics of amniotic fluid sludge in Japanese pregnant women with preterm labor and intact membranes.

METHODS

This was a retrospective study of 54 patients. The presence of amniotic fluid sludge was confirmed using transvaginal ultrasonography data during pregnancy. The following data were collected: gestational age, the presence of histologic chorioamnionitis, time from the diagnosis of threatened premature labor to delivery, oncofetal fibronectin (onfFN) levels, C-reactive protein peak value levels, cervical length at the time of onset of threatened premature labor and types of neonatal complications.

RESULTS

Significant differences (P = 0.03) were observed in the age at delivery in relation to the presence of amniotic sludge: delivery occurred at 28.3 ± 4.5 weeks and 31.7 ± 4.3 weeks in sludge positive patients and sludge-negative patients, respectively. Presence of sludge in patients diagnosed with histological chorioamnionitis at <37 weeks of gestation differed significantly (P = 0.01): sludge-positive, 81.8%; sludge-negative, 20.9%. Among the sludge-positive patients, 100% were positive for serum onfFN (≥50 ng/mL), whereas only 54% of sludge-negative patients were positive for serum onfFN (P = 0.03). Presence of amniotic fluid sludge did not significantly affect neonatal complications.

CONCLUSION

Our results confirmed previous findings that amniotic fluid sludge is a self-determining risk factor for preterm birth and chorioamnionitis in pregnant Japanese women.

Utility of cervical length and quantitative fetal fibronectin for predicting spontaneous preterm delivery among symptomatic nulliparous women

OBJECTIVE

To validate the utility of fetal fibronectin (fFN) and cervical length (CL) in predicting preterm delivery among symptomatic nulliparous women.

METHODS

A retrospective cohort study of nulliparous women who presented with uterine contractions, abdominal pain, or cervical change at 21-34 gestational weeks at Fukushima Medical University Hospital, Japan, between 2008 and 2017. fFN (categorized as <50 ng/dL, 50-199 ng/dL, >200 ng/dL) and CL (≥15 mm or <15 mm) were evaluated simultaneously. Adjusted odds ratios (aORs) and confidence intervals (CIs) for preterm delivery before 37 or 34 weeks, and delivery within 28 or 14 days were calculated (references: fFN, <50 ng/dL; CL, ≥15 mm).

RESULT

Among 285 women who met the study criteria, CL less than 15 mm was a risk factor for preterm delivery before 37 (aOR, 4.1; 95% CI, 1.1-6.7) and 34 (aOR, 6.8; 95% CI, 2.3-20.2) weeks. fFN of 200 ng/dL or higher was a risk factor for delivery within 28 (aOR, 19.8; 95% CI, 4.3-90.2) and 14 (aOR, 10.8; 95% CI, 1.7-67.6) days.

CONCLUSION

Among symptomatic nulliparous women, short CL was found to be a risk factor for preterm delivery and higher fFN levels were related to short gestational latency.

Acute Tocolysis - a Critical Analysis of Evidence-Based Data

Tocolysis is among the most common obstetric measures. The objective is to prolong the pregnancy by at least 48 hours to complete foetal lung maturation and for the in-utero transfer of the pregnant woman to a perinatal centre. The indication for tocolysis is regular, premature contractions (≥ 4/20 min) and a dynamic shortening of the cervical length/cervical opening between 22 + 0 to 33 + 6 weeks of pregnancy. In this connection, the cervical length measured on ultrasound and the determination of biomarkers in the cervicovaginal secretions can be important decision-making aids. Beta sympathomimetics should no longer be used due to the high rate of severe maternal adverse effects. Given controversial data, magnesium sulphate is no longer recommended for tocolysis in current guidelines. Atosiban is as effective for prolonging pregnancy as beta sympathomimetics and nifedipine, has the lowest rate of maternal adverse effects, but also the highest drug costs. Nifedipine and indomethacin are recommended in international guidelines for acute tocolysis, however there are indications of increased neonatal morbidity following indomethacin. Current problems are, above all, the lack of randomised, controlled comparative and placebo-controlled studies, the data which are controversial to some extent, and the insufficient evidence of tocolytics to significantly improve the neonatal outcome.

Prediction of preterm delivery in symptomatic women using PAMG-1, fetal fibronectin and phIGFBP-1 tests: systematic review and meta-analysis

OBJECTIVE

To assess the accuracy of placental alpha microglobulin-1 (PAMG-1), fetal fibronectin (fFN) and phosphorylated insulin-like growth factor-binding protein-1 (phIGFBP-1) tests in predicting spontaneous preterm birth (sPTB) within 7 days of testing in women with symptoms of preterm labor, through a systematic review and meta-analysis of the literature. The test performance of each biomarker was also assessed according to pretest probability of sPTB ≤ 7 days.

METHODS

The Cochrane, MEDLINE, PubMed and ResearchGate bibliographic databases were searched from inception until October 2017. Cohort studies that reported on the predictive accuracy of PAMG-1, fFN and phIGFBP-1 for the prediction of sPTB within 7 days of testing in women with symptoms of preterm labor were included. Summary receiver-operating characteristics (ROC) curves and sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and positive (LR+) and negative (LR-) likelihood ratios were generated using indirect methods for the calculation of pooled effect sizes with a bivariate linear mixed model for the logit of sensitivity and specificity, with each diagnostic test as a covariate, as described by the Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy.

RESULTS

Bivariate mixed model pooled sensitivity of PAMG-1, fFN and phIGFBP-1 for the prediction of sPTB ≤ 7 days was 76% (95% CI, 57-89%), 58% (95% CI, 47-68%) and 93% (95% CI, 88-96%), respectively; pooled specificity was 97% (95% CI, 95-98%), 84% (95% CI, 81-87%) and 76% (95% CI, 70-80%) respectively; pooled PPV was 76.3% (95% CI, 69-84%) (P < 0.05), 34.1% (95% CI, 29-39%) and 35.2% (95% CI, 31-40%), respectively; pooled NPV was 96.6% (95% CI, 94-99%), 93.3% (95% CI, 92-95%) and 98.7% (95% CI, 98-99%), respectively; pooled LR+ was 22.51 (95% CI, 15.09-33.60) (P < 0.05), 3.63 (95% CI, 2.93-4.50) and 3.80 (95% CI, 3.11-4.66), respectively; and pooled LR- was 0.24 (95% CI, 0.12-0.48) (P < 0.05), 0.50 (95% CI, 0.39-0.64) and 0.09 (95% CI, 0.05-0.16), respectively. The areas under the ROC curves for PAMG-1, fFN and phIGFBP-1 for sPTB ≤ 7 days were 0.961, 0.874 and 0.801, respectively.

CONCLUSIONS

In the prediction of sPTB within 7 days of testing in women with signs and symptoms of preterm labor, the PPV of PAMG-1 was significantly higher than that of phIGFBP-1 or fFN. Other diagnostic accuracy measures did not differ between the three biomarker tests. As prevalence affects the predictive performance of a diagnostic test, use of a highly specific assay for a lower-prevalence syndrome such as sPTB may optimize management. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

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 fibronectin to help decision-making in women with symptoms of preterm labour (QUIDS) part 1: Individual participant data meta-analysis and health economic analysis

INTRODUCTION

The aim of the QUIDS study is to develop a decision support tool for the management of women with symptoms and signs of preterm labour, based on a validated prognostic model using quantitative fetal fibronectin (qfFN) concentration, in combination with clinical risk factors.

METHODS AND ANALYSIS

The study will evaluate the Rapid fFN 10Q System (Hologic, Marlborough, Massachusetts) which quantifies fFN in a vaginal swab. In part 1 of the study, we will develop and internally validate a prognostic model using an individual participant data (IPD) meta-analysis of existing studies containing women with symptoms of preterm labour alongside fFN measurements and pregnancy outcome. An economic analysis will be undertaken to assess potential cost-effectiveness of the qfFN prognostic model. The primary endpoint will be the ability of the prognostic model to rule out spontaneous preterm birth within 7 days. Six eligible studies were identified by systematic review of the literature and five agreed to provide their IPD (n=5 studies, 1783 women and 139 events of preterm delivery within 7 days of testing).

ETHICS AND DISSEMINATION

The study is funded by the National Institute of Healthcare Research Health Technology Assessment (HTA 14/32/01). It has been approved by the West of Scotland Research Ethics Committee (16/WS/0068).

PROSPERO REGISTRATION NUMBER

CRD42015027590.

VERSION

Protocol version 2, date 1 November 2016.

The Rate of Cervical Length Shortening in the Management of Vasa Previa

OBJECTIVES

There is no consensus about the optimal surveillance strategy in women with a diagnosis of vasa previa. The aim of this study was to evaluate the role of the rate of change in cervical length measurements in the management of singleton pregnancies with a diagnosis of vasa previa.

METHODS

We performed a retrospective case-control study of our databases for pregnancies with a prenatal diagnosis of vasa previa that were followed with transvaginal sonography for cervical length and evaluated the impact of the changes in cervical length on the need for emergency cesarean delivery.

RESULTS

The cohort included 29 singleton pregnancies with a prenatal diagnosis of vasa previa in the second trimester. There were 14 and 15 pregnancies that underwent elective and emergency cesarean delivery, respectively. The rate of cervical length shortening was significantly slower for women with elective compared to emergency cesarean delivery (median [range], 0.7 [0.1-2.0] versus 1.5 [0.25-3.0] mm/wk; P = .011). For each additional millimeter-per-week decrease in cervical length, the odds of emergency cesarean delivery increased by 6.50 (95% confidence interval, 1.02-41.20). The receiver operating characteristic curve for the rate of cervical length shortening in the prediction of emergency cesarean delivery yielded an area under the curve of 0.85 (95% confidence interval, 0.69-0.99).

CONCLUSIONS

Our findings indicate an association between the rate of cervical length shortening and the risk of emergency cesarean delivery in pregnancies with a diagnosis of vasa previa in the second trimester. Further multicentric studies are required to validate our data prospectively and, in particular, the role of serial cervical length measurements in determining the optimal delivery time for individual cases.

Accuracy of fetal fibronectin for the prediction of preterm birth in symptomatic twin pregnancies: a pilot study

Our goal was to evaluate the performance of fetal fibronectin (fFN) test alone or combined with cervical length (CL), to predict spontaneous preterm birth (PTB) in symptomatic twin pregnancies. We carry out a short pilot study including all uncomplicated diamniotic twin pregnancies with symptoms of preterm labor (PTL) and intact membranes at 24-33 weeks + 6 days of gestation. Studied outcome were spontaneous delivery within 7 and 14 days of testing and spontaneous PTB at <34 and <37 weeks of gestation. Among 40 women, fFN test was positive in 3 of them (7.5%). Regardless of the outcome studied CL did not significantly predict PTB. Performance of fFN was sensitivity (66.7%), specificity (97.2%), positive predictive value (66.7%), negative predictive value (97.2%), positive likelihood ratio (LR) (24.0), and negative LR (0.3) to predict spontaneous PTB within 7 days (p = 0.01). Thus, 66.1% of patients with a positive fFN test would deliver within 7 days versus 2.4% if negative testing; starting with a pre-test probability of 7.5%. Combining CL and fFN did not enable to increase enough positive LR or decrease significantly negative LR. In conclusion, fFN test alone might have a better ability to detect spontaneous delivery within 7 days among symptomatic twin pregnancies.

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 cytokine network in women with an asymptomatic short cervix and the risk of preterm delivery

PROBLEM

To characterize the amniotic fluid (AF) inflammatory-related protein (IRP) network in patients with a sonographic short cervix (SCx) and to determine its relation to early preterm delivery (ePTD).

METHOD OF STUDY

A retrospective cohort study included women with a SCx (≤25 mm; n=223) who had amniocentesis and were classified according to gestational age (GA) at diagnosis and delivery (ePTD <32 weeks of gestation).

RESULTS

(i) In women with a SCx ≤ 22 1/7 weeks, the concentration of most IRPs increased as the cervix shortened; those with ePTD had a higher rate of increase in MIP-1α, MCP-1, and IL-6 concentrations than those delivering later; and (ii) the concentration of most IRPs and the correlation between several IRP pairs were higher in the ePTD group than for those delivering later.

CONCLUSION

Women with a SCx at 16-22 1/7 weeks have a unique AF cytokine network that correlates with cervical length at diagnosis and GA at delivery. This network may aid in predicting ePTD.

Placental inflammation and its relationship to cervicovaginal fetal fibronectin in preterm birth

OBJECTIVE

Late miscarriage and preterm birth are frequently thought to be associated with inflammation and infection, although in most cases the underlying cause of early delivery remains unknown. The placenta is the organ that links mother and fetus during pregnancy, and postnatal examination may provide useful information about pathophysiology. The relationship between placental pathological lesions and predictive markers of early delivery has not been explored. We sought to characterize preterm deliveries according to placental pathology and relate these to the performance of reliable predictive markers, fetal fibronectin and cervical length.

STUDY DESIGN

This is a retrospective subanalysis from a larger prospective cohort study on sonographic cervical length, quantitative fetal fibronectin and risk of spontaneous preterm birth. Our cohort was comprised of high-risk asymptomatic women attending the Prematurity Surveillance Clinic at St Thomas' Hospital between 2002 and 2015, who went on to have a late miscarriage or preterm delivery (16-36⁺⁶ weeks') and who had available placental histology. The placental pathology of these preterm deliveries was characterized according to the lesions identified, and categorized (according to the Redman classification) into inflammatory (e.g. chorioamnionitis) or non-inflammatory (histologically normal or vascular lesions indicating e.g. malperfusion). We sought to relate placental findings to the performance of reliable predictive markers, in women who delivered early. Standard clinical cut offs for cervical length (<25mm) and fetal fibronectin (>50ng/mL) were used to identify the proportion of preterm births that were accurately predicted by the tests or who showed a false negative result, in relation to their placental histology findings. Binomial logistic regression was carried out to evaluate the relationship between placental inflammation, quantitative fFN and cervical length as continuous variables.

RESULTS

105 women who had a late miscarriage or preterm delivery (16-36⁺⁶ weeks') and available placenta pathology were identified. 66% (42/64) of those with inflammatory placental pathology had a positive fetal fibronectin swab result compared to 15% (6/41) of those with non-inflammatory placental pathology (chi-squared 25.9, 95% CI 31.5 to 65.6, p<0.0001). A logistic regression model subanalysis of women in whom both CL and quantitative fFN results were available (n=66) revealed a highly statistically significant relationship with inflammatory placental lesions (p=0.003 and p=0.001 respectively). Placental inflammation was found to be associated with both increasing levels of fFN and a shortening cervix.

CONCLUSION

There is a significant association between a positive fetal fibronectin result and underlying inflammatory pathology of the placenta, even more so than the recognized relationship with short cervical length. Infective morbidity may be increased in women and neonates with positive fetal fibronectin who deliver preterm.

Influence of transvaginal ultrasound examination on quantitative vaginal fibronectin measurements: a prospective evaluation study

OBJECTIVE

The most important parameter in prediction of preterm birth is the cervical length measured by transvaginal ultrasound. In cases with mid-range cervical length (10-30 mm), prediction of preterm birth is difficult. In these cases, testing for cervicovaginal fluid fetal fibronectin (fFN) can improve prediction. However, it is unclear whether transvaginal ultrasound itself influences the fFN result. The purpose of this study was to evaluate this issue independent of gestational age and cervical length.

METHODS

A prospective evaluation study with 96 cases of pregnant women at 20-41 weeks of gestation was conducted in a tertiary perinatal center. A comparison of cervicovaginal fFN samples before and immediately after transvaginal ultrasound was performed. Fetal fibronectin was measured using the Hologic Rapid fFN 10Q system. It was analyzed quantitatively and qualitatively with ≥50 ng/mL as threshold for "positive". Changes in fFN values following transvaginal ultrasound were measured.

RESULTS

Ninety-six percent (69/72) of women with a fFN concentration of <26 ng/mL before ultrasound had a corresponding fFN value <26 ng/mL after ultrasound. Ninety-three percent (13/14) of women with a fFN concentration of ≥100 ng/mL before ultrasound had a corresponding fFN value ≥100 ng/mL after ultrasound. In 80% (4/5) of women with a positive fFN sample but with a value <100 ng/mL, it turned negative (<50 ng/mL) after ultrasound. For fFN concentrations ≥100 ng/mL, there are high random fluctuations in the measurement results.

CONCLUSIONS

Fetal fibronectin values of <26 ng/mL (for "negative") and ≥100 ng/mL (for "positive") from samples taken after ultrasound provide the same qualitative information as when sampled before ultrasound. For the correct interpretation however, quantitative analysis is necessary.

Contraction-based uterine artery Doppler velocimetry: novel approach for prediction of preterm birth in women with threatened preterm labor

OBJECTIVE

To evaluate whether uterine artery (UtA) Doppler velocimetry during peak uterine contraction is a useful marker for the prediction of preterm delivery.

METHODS

In this prospective cohort study, 172 patients admitted with preterm (24-35 weeks' gestation) uterine contractions were evaluated by UtA Doppler velocimetry during peak uterine contraction and by common obstetric measurements including cervical length. For UtA Doppler velocimetry, flow-velocity waveforms during peak uterine contraction (determined visually on tocodynamometry) were recorded during three consecutive heart cycles, and the mean UtA pulsatility index (UtA-PI) was calculated.

RESULTS

UtA-PI during the peak of contractions was significantly higher in patients who delivered within 7 days than in those who did not (P < 0.001). On receiver-operating characteristics curve analysis of UtA-PI on contraction, the areas under the curve for prediction of delivery within 48 h, 7 days or 14 days, ≤ 35 weeks and ≤ 37 weeks were 0.92, 0.88, 0.81, 0.83 and 0.74, respectively. Multiple regression analysis identified UtA-PI on contraction (P < 0.001) and cervical length (P < 0.001) as predictors of admission-to-delivery interval. The corresponding adjusted odds ratios for delivery within 7 days were 16.5 (95% CI, 5.7-47.2) for UtA-PI on contraction ≥ 1.32, and 14.7 (95% CI, 5.2-41.8) for cervical length ≤ 28 mm.

CONCLUSION

Use of UtA Doppler velocimetry during peak uterine contraction for patients exhibiting symptoms of preterm labor might be effective for the identification of pregnant women at risk of preterm delivery. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

The role of routine cervical length screening in selected high- and low-risk women for preterm birth prevention

Preterm birth remains a major cause of neonatal death and short and long-term disability in the US and across the world. The majority of preterm births are spontaneous and cervical length screening is one tool that can be utilized to identify women at increased risk who may be candidates for preventive interventions. The purpose of this document is to review the indications and rationale for CL screening to prevent preterm birth in various clinical scenarios. The Society for Maternal-Fetal Medicine recommends (1) routine transvaginal cervical length screening for women with singleton pregnancy and history of prior spontaneous preterm birth (grade 1A); (2) routine transvaginal cervical length screening not be performed for women with cervical cerclage, multiple gestation, preterm premature rupture of membranes, or placenta previa (grade 2B); (3) practitioners who decide to implement universal cervical length screening follow strict guidelines (grade 2B); (4) sonographers and/or practitioners receive specific training in the acquisition and interpretation of cervical imaging during pregnancy (grade 2B).

Effectiveness of a cervical pessary for women who did not deliver 48 h after threatened preterm labor (Assessment of perinatal outcome after specific treatment in early labor: Apostel VI trial)

BACKGROUND

Preterm birth is a major cause of neonatal mortality and morbidity. As preventive strategies are largely ineffective, threatened preterm labor is a frequent problem that affects approximately 10 % of pregnancies. In recent years, risk assessment in these women has incorporated cervical length measurement and fetal fibronectin testing, and this has improved the capacity to identify women at increased risk for delivery within 14 days. Despite these improvements, risk for preterm birth continues to be increased in women who did not deliver after an episode of threatened preterm labor, as indicated by a preterm birth rate between 30 to 60 % in this group of women. Currently no effective treatment is available. Studies on maintenance tocolysis and progesterone have shown ambiguous results. The pessary has not been evaluated in women with threatened preterm labor, however studies in asymptomatic women with a short cervix show reduced rates of preterm birth rates as well as perinatal complications. The APOSTEL VI trial aims to assess the effectiveness of a cervical pessary in women who did not deliver within 48 h after an episode of threatened preterm labor.

METHODS/DESIGN

This is a nationwide multicenter open-label randomized clinical trial. Women with a singleton or twin gestation with intact membranes, who were admitted for threatened preterm labor, at a gestational age between 24 and 34 weeks, a cervical length between 15 and 30 mm and a positive fibronectin test or a cervical length below 15 mm, who did not deliver after 48 h will be eligible for inclusion. Women will be allocated to a pessary or no intervention (usual care). Primary outcome is preterm delivery < 37 weeks. Secondary outcomes are amongst others a composite of perinatal morbidity and mortality. Sample size is based on an expected 50 % reduction of preterm birth before 37 weeks (two-sided test, α 0.05 and β 0.2). Two hundred women with a singleton pregnancy need to be randomized. Analysis will be done by intention to treat.

DISCUSSION

The APOSTEL VI trial will provide evidence whether a pessary is effective in preventing preterm birth in women who did not deliver 48 h after admission for threatened preterm labor and who remain at high risk for preterm birth.

TRIAL REGISTRATION

Trial is registered at the Dutch Trial Register: http://www.trialregister.nl , NTR4210, date of registration: October 16th 2013.

The impact of fetal gender and ethnicity on the risk of spontaneous preterm delivery in women with symptoms of preterm labor

OBJECTIVE

The objective of this study is to evaluate the relation among fetal gender, ethnicity, and preterm labor (PTL) and preterm delivery (PTD).

METHODS

A secondary analysis was performed of a prospective cohort study including women with symptoms of PTL between 24 and 34 weeks. The proportion of women carrying a male or female fetus at the onset of PTL was calculated. Gestational age at delivery and risk of PTD of both fetal genders was compared and interaction of fetal gender and maternal ethnicity on the risk of PTD was evaluated.

RESULTS

Of the 594 included women, 327 (55%) carried a male fetus. Median gestational age at delivery in women pregnant with a male fetus was 37 5/7 (IQR 34 4/7-39 1/7) weeks compared with 38 1/7 (IQR 36 0/7-39 5/7) weeks in women pregnant with a female fetus (p = 0.032). The risk of PTD did not differ significantly. In Caucasians, we did find an increased risk of PTD before 37 weeks in women pregnant with a male fetus (OR 1.9 (95% CI 1.2-3.0)).

CONCLUSIONS

The majority of women with PTL are pregnant with a male fetus and these women deliver slightly earlier. Race seems to affect this disparity.

Efficacy of midtrimester short cervix interventions is conditional on intraamniotic inflammation

BACKGROUND

Midtrimester ultrasound is a valuable method for identifying asymptomatic women at risk for spontaneous preterm delivery (PTD). However, response to various treatments (cerclage, progestogen) has been variable in the clinical setting. It remains unclear how other biomarkers may be used to guide intervention strategies.

OBJECTIVE

We applied an amniotic fluid inflammatory scoring system to determine if the degree of inflammation is associated with intervention efficacy in patients with midtrimester short cervix.

STUDY DESIGN

Women carrying a singleton fetus between 16-24 weeks' gestation with a short cervix (≤25 mm) on transvaginal ultrasound underwent amniocentesis and were assigned to McDonald cerclage, no cerclage, or weekly 17-alpha hydroxyprogesterone caproate (17OHP-C). Our previously described inflammatory risk score (comprised of 14 inflammatory markers) was used to classify patients as high (score ≥8) or low (score <8) risk for inflammation. Gestational age at delivery was compared for each intervention and risk score status. Risk of delivering as a function of the remaining gestation was evaluated using modified Cox proportional hazards models with incorporation of methods to account for both left and right truncation bias.

RESULTS

Ninety patients were included: 24 were in the nonintervention control group, 51 received cerclage, and 15 received 17OHP-C. Inflammation status at time of sampling influenced the efficacy of the treatment (P < .001). Compared to the nonintervention control group, in patients with low inflammation (score < 8), both cerclage (adjusted hazard ratio [HR], 2.86; 95% confidence interval [CI], 1.28-6.37) and 17OHP-C (HR, 3.11; 95% CI, 1.04-9.30) were associated with increased hazard of PTD. In contrast, in patients with high inflammation (score ≥8) both cerclage (HR, 0.22; 95% CI, 0.08-0.65) and 17OHP-C (HR, 0.20; 95% CI, 0.05-0.81) were associated with lower hazard of delivering preterm.

CONCLUSION

Cerclage placement or administration of 17OHP-C therapy for midtrimester short cervix for PTD prevention appears beneficial only in the subset of patients with high inflammation. Knowledge of the amniotic fluid inflammatory status may aid in guiding the appropriate therapy for women presenting with midtrimester short cervix who are at increased risk of PTD.

Development and validation of a tool incorporating cervical length and quantitative fetal fibronectin to predict spontaneous preterm birth in asymptomatic high-risk women

OBJECTIVE

To develop a predictive tool for spontaneous preterm birth (sPTB) in asymptomatic high-risk women that includes quantification of fetal fibronectin (fFN) along with cervical length (CL) measurement and other clinical factors.

METHODS

Data were analyzed that had been collected prospectively from 1249 women at high risk for sPTB attending preterm surveillance clinics. Clinicians were blinded to quantitative measurements of fFN (qfFN), although they were aware of qualitative fFN results. Parametric survival models for sPTB, with time-updated covariates, were developed and the best was selected using the Akaike and Bayesian information criteria. The model was developed on the first 624 consecutive women and validated on the subsequent 625. Fractional polynomials were used to accommodate possible non-linear effects of qfFN and CL. The estimated probability of delivery before 30, 34 or 37 weeks' gestation and within 2 or 4 weeks of testing was calculated for each patient and analyzed as a predictive test for the actual occurrence of each event. Predictive statistics were calculated to compare training and validation sets.

RESULTS

The final model that was selected used a log-normal survival curve with CL, √qfFN and previous sPTB/preterm prelabor rupture of membranes as predictors. Predictive statistics were similar for training and validation sets. Areas under the receiver-operating characteristics curves ranged from 0.77 to 0.99, indicating accurate prediction across all five delivery outcomes.

CONCLUSIONS

sPTB in high-risk asymptomatic women can be predicted accurately using a model combining qfFN and CL, which supersedes the single-threshold fFN test, demographic information and obstetric history. This algorithm has been incorporated into an App (QUiPP) for widespread use.

An elevated amniotic fluid prostaglandin F2α concentration is associated with intra-amniotic inflammation/infection, and clinical and histologic chorioamnionitis, as well as impending preterm delivery in patients with preterm labor and intact membranes

OBJECTIVE

To determine whether an elevated amniotic fluid concentration of prostaglandin F2α (PGF2α) is associated with intra-amniotic inflammation/infection and adverse pregnancy outcomes in patients with preterm labor and intact membranes.

MATERIALS AND METHODS

The retrospective cohort study included 132 patients who had singleton pregnancies with preterm labor (< 35 weeks of gestation) and intact membranes. Amniotic fluid was cultured for aerobic and anaerobic bacteria as well as for genital mycoplasmas. Intra-amniotic inflammation was defined by an elevated amniotic fluid matrix metalloproteinase-8 (MMP-8) concentration (>23 ng/mL). PGF2α was measured with a sensitive and specific immunoassay. The amniotic fluid PGF2α concentration was considered elevated when it was above the 95th percentile among pregnant women at 15-36 weeks of gestation who were not in labor (≥170 pg/mL).

RESULTS

(1) The prevalence of an elevated amniotic fluid PGF2α concentration was 40.2% (53/132) in patients with preterm labor and intact membranes; (2) patients with an elevated amniotic fluid PGF2α concentration had a significantly higher rate of positive amniotic fluid culture [19% (10/53) versus 5% (4/79); p = 0.019], intra-amniotic inflammation/infection [49% (26/53) versus 20% (16/79); p = 0.001], spontaneous preterm delivery, clinical and histologic chorioamnionitis, and funisitis, as well as a higher median amniotic fluid MMP-8 concentration and amniotic fluid white blood cell count and a shorter amniocentesis-to-delivery interval than those without an elevated concentration of amniotic fluid PGF2α (p < 0.05 for each); and (3) an elevated amniotic fluid PGF2α concentration was associated with a shorter amniocentesis-to-delivery interval after adjustment for the presence of intra-amniotic inflammation/infection [hazard ratio 2.1, 95% confidence interval (CI) 1.4-3.1; p = 0.001].

CONCLUSION

The concentration of PGF2α was elevated in the amniotic fluid of 40.2% of patients with preterm labor and intact membranes and is an independent risk factor for intra-amniotic inflammation/infection, impending preterm delivery, chorioamnionitis, and funisitis.

Population differences and the effect of vaginal progesterone on preterm birth in women with threatened preterm labor (.)

OBJECTIVE

Threatened preterm labor (tPTL) is a complication of pregnancy. Identification of women and clinical definition differs between countries. This study investigated differences in tPTL and effectiveness of vaginal progesterone to prevent preterm birth (PTB) between two countries.

METHODS

Secondary analysis of a randomized controlled trial (RCT) from Argentina and Switzerland comparing vaginal progesterone to placebo in women with tPTL (n = 379). Cox proportional hazards analysis was performed to compare placebo groups of both countries and to compare progesterone to placebo within each country. We adjusted for baseline differences. Iatrogenic onset of labor or pregnancy beyond gestational age of interest was censored.

RESULTS

Swiss and Argentinian women were different on baseline. Risks for delivery <14 days and PTB < 34 and < 37 weeks were increased in Argentina compared to Switzerland, HR 3.3 (95% CI 0.62-18), 54 (95% CI 5.1-569) and 3.1 (95% CI 1.1-8.4). In Switzerland, progesterone increased the risk for delivery <14 days [HR 4.4 (95% CI 1.3-15.7)] and PTB <37 weeks [HR 2.5 (95% CI 1.4-4.8)], in Argentina there was no such effect.

CONCLUSION

In women with tPTL, the effect of progesterone may vary due to population differences. Differences in populations should be considered in multicenter RCTs.

Abnormal Middle Cerebral Artery Doppler Associates with Spontaneous Preterm Birth in Normally Grown Fetuses

OBJECTIVE

Our aim was to evaluate whether Doppler changes in the fetal middle cerebral (MCA) and umbilical arteries (UA) suggesting fetal hypoxemia precede the onset of spontaneous preterm birth (PTB).

METHODS

We studied 2,340 appropriate-for-gestational-age singleton pregnancies that had MCA and UA pulsatility indices (PI) recorded at 28-32 weeks. Values including the cerebroplacental ratio (CPR) were converted into multiples of the median and evaluated according to both gestational age at the onset of labor and the interval between ultrasound and labor. ROC analysis was used to calculate the ability in the prediction of spontaneous PTB before 32, 34 and 37 weeks' gestation.

RESULTS

While no correlations were observed for the UA PI and CPR, lower MCA PI values were associated with an earlier onset of labor (p < 0.001) and a shorter ultrasound-labor interval (p = 0.028). The ROC analysis at different gestational ages and intervals to labor indicated that MCA PI values were poorly predictive of spontaneous PTB (all areas under the curve <0.7).

CONCLUSIONS

Low MCA PI values at 28-32 weeks are associated with subsequent spontaneous PTB, indicating that fetal hypoxemia unrelated with placental disease might be implicated in the onset of labor. This association, however, is unlikely to be useful in the prediction of PTB.

Using ultrasound in the clinical management of placental implantation abnormalities

Placental implantation abnormalities, including placenta previa, placenta accreta, vasa previa, and velamentous cord insertion, can have catastrophic consequences for both mother and fetus, especially as pregnancy progresses to term. In these situations, current recommendations for management usually call for an indicated preterm delivery even in asymptomatic patients. However, the recommended gestational age(s) for delivery in asymptomatic patients are empirically determined without consideration of the recent literature regarding the usefulness of specific ultrasound findings to help individualize management. The purpose of this article is to propose literature-supported guidelines to the current opinion-based management of asymptomatic patients with placental implantation abnormalities based on relevant and specific ultrasound findings such as cervical length, distance between the internal cervical os and placenta, and placental edge thickness.

Sterile intra-amniotic inflammation in asymptomatic patients with a sonographic short cervix: prevalence and clinical significance

OBJECTIVE

To determine the frequency and clinical significance of sterile and microbial-associated intra-amniotic inflammation in asymptomatic patients with a sonographic short cervix.

METHODS

Amniotic fluid (AF) samples obtained by transabdominal amniocentesis from 231 asymptomatic women with a sonographic short cervix [cervical length (CL) ≤25 mm] were analyzed using cultivation techniques (for aerobic and anaerobic as well as genital mycoplasmas) and broad-range polymerase chain reaction (PCR) coupled with electrospray ionization mass spectrometry (PCR/ESI-MS). The frequency and magnitude of intra-amniotic inflammation [defined as an AF interleukin (IL)-6 concentration ≥2.6 ng/mL], acute histologic placental inflammation, spontaneous preterm delivery (sPTD), and the amniocentesis-to-delivery interval were examined according to the results of AF cultures, PCR/ESI-MS and AF IL-6 concentrations.

RESULTS

Ten percent (24/231) of patients with a sonographic short cervix had sterile intra-amniotic inflammation (an elevated AF IL-6 concentration without evidence of microorganisms using cultivation and molecular methods). Sterile intra-amniotic inflammation was significantly more frequent than microbial-associated intra-amniotic inflammation [10.4% (24/231) versus 2.2% (5/231); p < 0.001]. Patients with sterile intra-amniotic inflammation had a significantly higher rate of sPTD <34 weeks of gestation [70.8% (17/24) versus 31.6% (55/174); p < 0.001] and a significantly shorter amniocentesis-to-delivery interval than patients without intra-amniotic inflammation [median 35, (IQR: 10-70) versus median 71, (IQR: 47-98) days, (p < 0.0001)].

CONCLUSION

Sterile intra-amniotic inflammation is more common than microbial-associated intra-amniotic inflammation in asymptomatic women with a sonographic short cervix, and is associated with increased risk of sPTD (<34 weeks). Further investigation is required to determine the causes of sterile intra-amniotic inflammation and the mechanisms whereby this condition is associated with a short cervix and sPTD.