Prediction of preterm delivery among women with threatened preterm labor

Recent Advances and Challenges in the Early Diagnosis and Treatment of Preterm Labor

Preterm birth (PTB) is the primary cause of neonatal mortality and long-term disabilities. The unknown mechanism behind PTB makes diagnosis difficult, yet early detection is necessary for controlling and averting related consequences. The primary focus of this work is to provide an overview of the known risk factors associated with preterm labor and the conventional and advanced procedures for early detection of PTB, including multi-omics and artificial intelligence/machine learning (AI/ML)- based approaches. It also discusses the principles of detecting various proteomic biomarkers based on lateral flow immunoassay and microfluidic chips, along with the commercially available point-of-care testing (POCT) devices and associated challenges. After briefing the therapeutic and preventive measures of PTB, this review summarizes with an outlook.

Biomarkers for Preterm Delivery

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

Does Assessment of Cervical Phosphorylated Insulin-like Growth Factor Binding Protein-1 by Bedside Vaginal Swab Test Really Predict Preterm Birth?

Preterm birth is the first cause of neonatal mortality and is associated with elevated risks of long-term complications such as neurodevelopmental impairment. Prediction of spontaneous preterm birth, one of the biggest challenges in obstetrics, aims at delaying birth in order to allow corticosteroid therapy and, if necessary, transfer of patient to a higher-level maternity care unit. We aimed to assess the predictive role of phIGFBP-1 (Actim® Partus) diagnostic test on patients at risk of preterm labor, routinely used in our institution. We conducted a retrospective cohort study on 99 patients admitted in the high-risk pregnancy unit of our institution from June 2012 to November 2014. The primary outcome measures were delivery before 34⁺⁰ and 37⁺⁰ weeks. Data analysis allowed measure of Actim® Partus test sensitivity (Se), specificity (Sp), positive and negative predictive values (PPV and NPV), diagnostic efficiency as well as positive and negative likelihood ratios. Actim® Partus test features (Se, Sp, PPV and NPV) were 53.3, 67.9, 23.5 and 88.7% respectively for deliveries occurring ≤ 34⁺⁰ weeks and 54.2, 75.4, 55.8, and 74.2%, respectively, for deliveries occurring ≤ 37⁺⁰ weeks. Diagnostic efficiency of the test was 65.7% (≤ 34⁺⁰ weeks) and 67.7% (≤ 37⁺⁰ weeks). Positive likelihood ratios were 1.6 (≤ 34⁺⁰ weeks) and 2.2 (≤ 37⁺⁰ weeks). Negative likelihood ratios were 0.7 (≤ 34⁺⁰ weeks) and 0.6 (≤ 37⁺⁰ weeks). Results of our study show that phIGFBP-1 diagnostic test is not accurate enough in predicting preterm birth before 34⁺⁰ or 37⁺⁰ weeks, and therefore, there is little clinical interest in its everyday use.

Three biomarker tests to help diagnose preterm labour: a systematic review and economic evaluation

BACKGROUND

Preterm birth may result in short- and long-term health problems for the child. Accurate diagnoses of preterm births could prevent unnecessary (or ensure appropriate) admissions into hospitals or transfers to specialist units.

OBJECTIVES

The purpose of this report is to assess the test accuracy, clinical effectiveness and cost-effectiveness of the diagnostic tests PartoSure™ (Parsagen Diagnostics Inc., Boston, MA, USA), Actim^® Partus (Medix Biochemica, Espoo, Finland) and the Rapid Fetal Fibronectin (fFN)^® 10Q Cassette Kit (Hologic, Inc., Marlborough, MA, USA) at thresholds ≠50 ng/ml [quantitative fFN (qfFN)] for women presenting with signs and symptoms of preterm labour relative to fFN at 50 ng/ml.

METHODS

Systematic reviews of the published literature were conducted for diagnostic test accuracy (DTA) studies of PartoSure, Actim Partus and qfFN for predicting preterm birth, the clinical effectiveness following treatment decisions informed by test results and economic evaluations of the tests. A model-based economic evaluation was also conducted to extrapolate long-term outcomes from the results of the diagnostic tests. The model followed the structure of the model that informed the 2015 National Institute for Health and Care Excellence guidelines on preterm labour diagnosis and treatment, but with antenatal steroids use, as opposed to tocolysis, driving health outcomes.

RESULTS

Twenty studies were identified evaluating DTA against the reference standard of delivery within 7 days and seven studies were identified evaluating DTA against the reference standard of delivery within 48 hours. Two studies assessed two of the index tests within the same population. One study demonstrated that depending on the threshold used, qfFN was more or less accurate than Actim Partus, whereas the other indicated little difference between PartoSure and Actim Partus. No study assessing qfFN and PartoSure in the same population was identified. The test accuracy results from the other included studies revealed a high level of uncertainty, primarily attributable to substantial methodological, clinical and statistical heterogeneity between studies. No study compared all three tests simultaneously. No clinical effectiveness studies evaluating any of the three biomarker tests were identified. One partial economic evaluation was identified for predicting preterm birth. It assessed the number needed to treat to prevent a respiratory distress syndrome case with a 'treat-all' strategy, relative to testing with qualitative fFN. Because of the lack of data, our de novo model involved the assumption that management of pregnant women fully adhered to the results of the tests. In the base-case analysis for a woman at 30 weeks' gestation, Actim Partus had lower health-care costs and fewer quality-adjusted life-years (QALYs) than qfFN at 50 ng/ml, reducing costs at a rate of £56,030 per QALY lost compared with qfFN at 50 ng/ml. PartoSure is less costly than Actim Partus while being equally effective, but this is based on diagnostic accuracy data from a small study. Treatment with qfFN at 200 ng/ml and 500 ng/ml resulted in lower cost savings per QALY lost relative to fFN at 50 ng/ml than treatment with Actim Partus. In contrast, qfFN at 10 ng/ml increased QALYs, by 0.002, and had a cost per QALY gained of £140,267 relative to fFN at 50 ng/ml. Similar qualitative results were obtained for women presenting at different gestational ages.

CONCLUSION

There is a high degree of uncertainty surrounding the test accuracy and cost-effectiveness results. We are aware of four ongoing UK trials, two of which plan to enrol > 1000 participants. The results of these trials may significantly alter the findings presented here.

STUDY REGISTRATION

The study is registered as PROSPERO CRD42017072696.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Prediction of preterm labour from a single blood test: The role of the endocannabinoid system in predicting preterm birth in high-risk women

OBJECTIVE

To determine if plasma concentrations of the N-acylethanolamines (NAEs) N-arachidonoylethanolamine (AEA), N-oleoylethanolamide (OEA) and N-palmitoylethanolamide (PEA) increase in women at high risk for preterm birth (PTB) and whether these could be used to predict preterm delivery and if so, how they compare with current methods.

DESIGN

Prospective cohort study.

SETTING

A large UK teaching hospital.

POPULATION

217 pregnant women were recruited between 24 and 34 gestational weeks at 'high-risk' for PTB, recruited from a prematurity prevention clinic or antenatal wards.

METHODS

Plasma AEA, OEA, and PEA concentrations were measured using ultra-high performance liquid chromatography-tandem mass spectrometry whilst FAAH enzyme activity was measured by fluorometric radiometric assay and CL by ultrasound scan. The clinical usefulness of these measurements were determined by ROC and multivariate analyses.

RESULTS

AEA and PEA concentrations were significantly higher in women who delivered prematurely. An AEA concentration >1.095 nM predicted PTB, the gestational age at delivery and the recruitment to delivery interval (RTDI). A PEA concentration >17.50 nM only predicted PTB; FAAH enzyme activity was not related to these changes. Multivariate analysis (all variables) generated an equation to accurately predict the RTDI.

CONCLUSIONS

A single plasma AEA or PEA measurement can predict PTB. A single AEA measurement predicts the gestational age of delivery and the remaining period of pregnancy with reasonable accuracy and better than existing conventional tests thus offering a better window for primary prevention of PTB.

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.

Accuracy of a combined insulin-like growth factor-binding protein-1/interleukin-6 test (Premaquick) in predicting delivery in women with threatened preterm labor

PURPOSE

To determine values of combinations of interleukin-6 (IL-6)/cervical native insulin-like growth factor-binding protein-1 (IGFBP-1)/total IGFBP-1 (Premaquick©) in predicting spontaneous deliveries and spontaneous exclusive preterm deliveries in women with threatened preterm labor.

METHODS

Women with singleton pregnancies between gestation age (GA) of 24 weeks and 36 weeks and 6 days with preterm labor were recruited during a prospective multicenter study. Premaquick© was positive when at least two of three biomarkers were positive. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were estimated for both prediction of spontaneous deliveries and spontaneous exclusive preterm deliveries.

RESULTS

Ninety-seven (99.0%) out of 98 women enrolled were analyzed. Based on delivery status 7/14 days post-enrollment of general study population, Premaquick© had a sensitivity of 87.1/85.7%, a specificity of 92.4/96.8%, a PPV of 84.4/93.8% and a NPV of 93.9/92.3% for prediction of spontaneous delivery. Predictive accuracy of Premaquick© test in relation to days of enrollment were: 90.7% (≤7 days) and 92.8% (≤14 days). For women enrolled at GA <35 weeks, Premaquick© had a sensitivity of 100.0/87.5%, a specificity of 94.1/96.9%, a PPV of 70.5/87.5%, a NPV of 100.0/96.9% and an accuracy of 95.0/95.0% for prediction of preterm delivery within 7/14 days of enrollment, respectively. PPV was most significantly different in both groups when outcomes were compared between 2 days and 14 days post-enrollment (P<0.001).

CONCLUSION

This novel triple biomarker model of native and total IGFBP-1 and IL-6 appears to be an accurate test in predicting spontaneous deliveries and spontaneous exclusive preterm deliveries in threatened preterm labor in singleton pregnancies.

Cervical phosphorylated insulin-like growth factor binding protein-1 test for the prediction of preterm birth: a systematic review and metaanalysis

OBJECTIVE

To assess the accuracy of the cervical phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) test to predict preterm birth in women with and without symptoms of preterm labor through the use of formal methods for systematic reviews and metaanalytic techniques.

DATA SOURCES

PubMed, Embase, Cinahl, Lilacs, and Medion (all from inception to June 30, 2015), reference lists, conference proceedings, and Google scholar.

STUDY ELIGIBILITY CRITERIA

Cohort or cross-sectional studies that reported on the predictive accuracy of the cervical phIGFBP-1 test for preterm birth.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two reviewers independently selected studies, assessed the risk of bias, and extracted the data. Summary receiver-operating characteristic curves, pooled sensitivities and specificities, and summary likelihood ratios were generated.

RESULTS

Forty-three studies met the inclusion criteria, of which 15 provided data on asymptomatic women (n = 6583) and 34 on women with an episode of preterm labor (n = 3620). Among asymptomatic women, the predictive accuracy of the cervical phIGFBP-1 test for preterm birth at <37, <34, and <32 weeks of gestation was minimal, with pooled sensitivities and specificities and summary positive and negative likelihood ratios ranging from 14% to 47%, 76% to 93%, 1.5 to 4.4, and 0.6 to 1.0, respectively. Among women with an episode of preterm labor, the test had a low predictive performance for delivery within 7 and 14 days of testing, and preterm birth at <34 and <37 weeks of gestation with pooled sensitivities and specificities and summary positive and negative likelihood ratios that varied between 60% and 68%, 77% and 81%, 2.7 and 3.5, and 0.4 and 0.5, respectively. A negative test result in women with an episode of preterm labor had a low to moderate accuracy to identify women who are not at risk for delivering within the next 48 hours (summary negative likelihood ratio of 0.28 in all women and 0.23 in women with singleton gestations).

CONCLUSION

Cervical phIGFBP-1 has the potential utility to identify patients with an episode of preterm labor who will not deliver within 48 hours. However, its overall predictive ability for the identification of symptomatic and asymptomatic women at risk for preterm birth is limited.

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.

Evaluation of the ability of cervical length and fetal fibronectin measurement to predict preterm delivery in asymptomatic women with risk factors

OBJECTIVE

To evaluate the power of transvaginal ultrasound cervical length (CL) and fetal fibronectin (fFN) measurement for the prediction of preterm delivery (PTD) in asymptomatic women with risk factors.

METHODS

Between January 2010 and October 2012, 218 women with singleton pregnancies and a high risk for PTD (i.e. prior history of PTD, cervical surgeries, late miscarriages, uterine abnormalities or premature rupture of the membranes) were selected. CL was measured by transvaginal ultrasonography between 14 and 22 weeks, and a CL<2.5 cm was considered to be short. The fFN was measured with a sterile speculum examination. The primary outcome was the spontaneous PTD rate at <34(+0) and <37(+0) weeks, and the PTD rate was analyzed by either of two methods alone or combined.

RESULTS

There were 213 cases included in the analysis, and 47 women (22.1%) had positive fFN. The average CL of women with positive fFN (2.3 ± 0.9 cm) was significantly shorter than that of women with negative fFN (3.1 ± 0.8 cm; p=0.02). There were 25 (11.7%) and 38 (18.8%) cases with PTD at <34(+0) and <37(+0) weeks, respectively. By individual analyses, the highest PTD rate was 51.2% in women with positive fFN at <37(+0) weeks. The sensitivity and diagnostic efficiency values for PTD prediction by CL were low at <34(+0) and <37(+0) weeks. The values of diagnostic efficiency by fFN were >80% at <34(+0) and <37(+0) weeks. In the combined analysis, the highest PTD rate was 57.1% in women with CL ≤ 2.5 cm and positive fFN at <37(+0) weeks. The Kaplan-Meier curve indicated that there were significant differences among the four groups (χ(2)=54.261; p=0.000).

CONCLUSIONS

These results indicate a significant correlation between fFN and PTD prediction. The PTD prediction could be enhanced by combined CL and fFN measurement.

Rapid cervical phIGFBP-1 test in asymptomatic twin pregnancies: role in mid-pregnancy prediction of spontaneous preterm delivery

Objective This study aimed to assess the accuracy of a second-trimester rapid cervical phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) test to predict spontaneous preterm delivery in asymptomatic twin pregnancies. Method During the second trimester, a rapid test to detect phIGFBP-1 in cervical secretions was performed on consecutive twin pregnancies between 2009 and 2011, to evaluate its predictive value for spontaneous preterm delivery at <28, <30, <32 and <34 weeks' gestation. Excluded were patients with cerclage, pessary or undergoing indicated preterm delivery. Results A total of 197 pregnancies fulfilled the study criteria and were tested at a median gestational age of 20.3 weeks (interquartile range: 20-20.6). Median gestational age at delivery was 36.4 weeks. Spontaneous preterm delivery at <34 weeks occurred in 21 (10.7%) cases, at <32 weeks in 9 (4.5%), at <30 weeks in 6 (3%) and at <28 weeks in 4 (2%). Seventeen patients (8.7%) were test positive: In this group, three patients delivered before 34 weeks' gestation, whereas none delivered at <32 weeks. The sensitivity, specificity, positive and negative predictive value of the test for spontaneous preterm delivery <34 weeks were 14% (95% confidence interval, 3-37%), 92% (86-95%), 17% (4-44%) and 90% (84-93%), respectively, with a positive and negative likelihood ratio of 1.79 (0.56-5.74) and 0.93 (0.78-1.10). Conclusions In the second trimester, rapid cervical phIGFBP-1 testing in asymptomatic twin pregnancies has a poor performance in predicting spontaneous preterm delivery.

The short-term prediction of preterm birth: a systematic review and diagnostic metaanalysis

OBJECTIVE

To assess the diagnostic accuracy of fetal fibronectin (fFN), fetal breathing movements (FBM), and cervical length (CL) for the short-term prediction of preterm birth in symptomatic patients.

STUDY DESIGN

Diagnostic metaanalysis using bivariate methods.

RESULTS

Pooled sensitivities for fFN, FBM, and CL for delivery within 48 hours of testing were 0.62 (95% confidence interval [CI], 0.43-0.78), 0.75 (95% CI, 0.57-0.87) and 0.77 (95% CI, 0.54-0.90), respectively. Pooled specificities for fFN, FBM, and CL for delivery within 48 hours were 0.81 (95% CI, 0.74-0.86), 0.93 (95% CI, 0.75-0.98) and 0.88 (95% CI, 0.84-0.91). Pooled sensitivities for fFN, FBM, and CL for delivery within 7 days were 0.75 (95% CI, 0.69-0.80), 0.67 (95% CI, 0.43-0.84), and 0.74 (95% CI, 0.58-0.85). Pooled specificities for fFN, FBM, and CL for delivery within 7 days were 0.79 (95% CI, 0.76-0.83), 0.98 (95% CI, 0.83-1.00) and 0.89 (95% CI, 0.85-0.92). Based on a pretest probability of 10% for delivery within 48 hours, posttest probabilities (positive and negative) were 27% and 5% for fFN, 54% and 3% for fFN, and 42% and 3% for CL. For a pretest probability of 20% for delivery within 7 days, posttest probabilities (positive and negative) were 48% and 7% for fFN, 89% and 8% for FBM, and 63% and 7% for CL.

CONCLUSION

In symptomatic patients, for fFN, absence of FBM, and CL have diagnostic use as predictors of delivery within 48 hours and within 7 days of testing. Absence of FBM appears to be the best test for predicting preterm birth.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

II.

Improving the screening accuracy for preterm labor: is the combination of fetal fibronectin and cervical length in symptomatic patients a useful predictor of preterm birth? A systematic review

OBJECTIVE

Our objective was to systematically review the current medical literature to assess the accuracy of the combination of fetal fibronectin (fFN) plus ultrasound assessment of cervical length (CL) as screening tools for preterm labor and prediction of preterm birth (PTB), and to compare this to the traditional clinical method of digital cervical examination.

STUDY DESIGN

We searched PubMed and Cochrane databases without date restriction using the key words "fibronectin" and "cervical length," limited to human studies published in English. In all, 85 studies were identified and supplemented by 1 additional study found through bibliographic search.

RESULTS

Nine studies reported the association between fFN positivity plus CL measurement with PTB in women presenting with symptomatic uterine contractions. We conducted an analytic review of the sensitivity, specificity, positive predictive value, and negative predictive value of fFN plus CL for PTB. Further metaanalysis was not performed due to study heterogeneity, especially with respect to the range of gestational ages and variations in cutoff values for the diagnosis of short cervix. Although the clinical diagnostic methodology of preterm labor diagnosis by documenting uterine contractions plus cervical change is currently standard practice, a newer approach combining fFN and CL screening results in a higher sensitivity and positive predictive value for PTB risk while maintaining high negative predictive value.

CONCLUSION

We conclude that this combined screening approach yields useful information regarding short-term risks that can be used to guide acute management, and effectively identifies a population at low risk in whom expensive and potentially dangerous interventions could be avoided.

Early pregnancy vaginal fluid phosphorylated insulin-like growth factor binding protein-1 predicts preterm delivery

OBJECTIVE

We aimed to study vaginal fluid phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) testing in early pregnancy to predict spontaneous preterm delivery (PTD).

METHODS

Vaginal and cervical swab samples were collected from 5180 unselected women during the first-trimester (mean gestational age 13.1 weeks) ultrasound screening. PhIGFBP-1 was measured in vaginal and cervical fluid by an immunoenzymometric assay. Concentrations of ≥10 µg/L were considered elevated. The outcome measure was spontaneous PTD at <32 or <37 weeks gestation.

RESULTS

The median concentrations of first-trimester vaginal and cervical phIGFBP-1 were higher in women with spontaneous PTD at <32 and <37 weeks gestation. When 10 µg/L of phIGFBP-1 was used as a cut-off level, the OR in predicting PTD at <32 weeks gestation was 8.6 (95% CI 3.6-20.7) for vaginal samples and 3.6 (95% CI 1.7-7.9) for cervical samples. At <37 weeks gestation, the OR in predicting PTD was 3.0 (95% CI 1.9-3.9) for vaginal samples and 1.9 (95% CI 1.4-2.5) for cervical samples. In multiple logistic regression analysis, both elevated vaginal and cervical fluid phIGFBP-1 levels were independent predictors of PTD both at <32 and <37 weeks gestation.

CONCLUSION

First-trimester vaginal phIGFBP-1 performed better than cervical phIGFBP-1 in the prediction of spontaneous PTD.

Diagnostic accuracy of rapid phIGFBP-I assay for predicting preterm labor in symptomatic patients

OBJECTIVE

To estimate sensitivity, specificity, positive and negative predictive values (PPV, NPV) of insulin-like growth factor binding protein-1 (phIGFBP-1) test in predicting preterm delivery in women with symptoms of preterm labor. Secondary objectives were to compare test characteristics of the phIGFBP-1 and fetal fibronectin (fFN) tests.

STUDY DESIGN

Labor and delivery units in two Calgary hospitals. Subjects were 349 women with suspected labor between 24 and 35 weeks gestational age (GA). Women had cervical phIGFBP-1 test +/- and fFN testing. Sensitivity, specificity, PPV and NPV were estimated. Primary outcome was birth <37 weeks GA.

RESULT

Sensitivity of phIGFBP-1 test for delivery <37 weeks was 0.39; specificity, 0.76; PPV, 0.24; NPV, 0.86. NPV of phIGFBP-1 did not differ greatly from that of fFN testing (0.88).

CONCLUSION

NPV did not differ between phIGFBP-1 and fFN for delivery <37 weeks. Neither test improves on pretest probability of delivery <37 weeks, so clinicians must decide whether the use of either test is justified.

The role of insulin-like growth factor in prediction and prevention of preterm delivery

BACKGROUND/AIM

Prediction and prevention of preterm delivery remain great challenge. It is important to include in everyday medical practice determination of certain markers that could help identifying pregnant women with preterm delivery. Insulinlike growth factor (IGF) is involved in the control mechanism of fetal and placental growth and development. The aim of this study was to examine the presence of insulin-like growth factor binding protein 1 (IGFBP-1) in cervicovaginal secretion of pregnant women with symptoms of preterm labor, but with apparently intact fetal membranes and to point out a possible application of the strip test for detection of phlGFBP-1 in diagnosis of preterm premature rupture of total membranes (PPROM) in everyday medical practice.

METHODS

The study was performed at the Department for Obstetrics and Gynecology, Clinical Center of Vojvodina between October 2008 and May 2009. The study included 54 pregnant women between 20-35 weeks of gestation (WG), divided into two groups: the study group (16 pregnant women with symptoms of preterm delivery that gave birth before 37 WG) and the control group (38 pregnant women with the normal course of pregnancy that gave birth on term). In cervicovaginal secretion of the examined pregnant women the level of IGFBP-1 was determined by the immunochromatographic assay with monoclonal antibodies 6303 as a detecting antibody (Actim PROM test, Medix Biochemica, Kauniainen, Finland).

RESULTS

Gestational age (GA) at delivery in the study group was 32.6 WG and in the control group it was 38.4 WG. Weight of newborns in the study group was 2,021 g and in the control group 3,430 g. IGFBP test was positive in 15 women (93.75%) of the study group, while in the control group it was positive only in 1 woman (2.63%).

CONCLUSION

Test on phIGFBP-1 in cervicovaginal mucus was positive in 93.75% women with preterm delivery, suggesting that this test could be used in diagnosis of silent rupture of fetal membranes and in prediction of preterm delivery.

The combination of short cervical length and phIGFBP-1 in the prediction of preterm delivery in symptomatic women

OBJECTIVE

To assess the combined use of cervical length and cervical phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) in the prediction of preterm delivery in symptomatic women.

METHODS

Cervical length was prospectively measured in 102 consecutive singleton pregnancies with intact membranes and regular contractions at 24-32 weeks, and phIGFBP-1 was assessed in those with a cervix ≤30 mm.

RESULTS

Among women with a cervix >30 mm (n = 42), none delivered <34 weeks or within 7 days. Among women with a cervical length ≤30 mm (n = 60), eight delivered <34 weeks, four of which within 7 days. A positive phIGFBP-1 conferred a significantly increased risk of delivery before 34 weeks in women with a cervix ≤30 mm (likelihood ratio 2.32, 95% confidence interval 1.15-4.67), and a significantly increased risk of delivering within 7 days in the subgroup of women with a cervical length of 20-30 mm (likelihood ratio 3.64, 95% confidence interval 2.20-6.01).

CONCLUSIONS

In symptomatic women with a cervical length >30 mm the risk of preterm delivery is very low. In women with a cervix ≤30 mm, adding phIGFBP-1 assessment may improve the risk assessment for preterm delivery, and help to plan subsequent pregnancy management.

The role of phosphorylated insulin-like growth factor binding protein-1 in predicting pre-term labour in twin pregnancies

This was a retrospective study, carried out at Yeovil District Hospital, UK, from January 2006 to December 2008, looking at 40 patients with twin pregnancies. The aim was to evaluate the role of phosphorylated insulin-like growth factor binding protein-1 (IGFBP-1) test in the prediction of pre-term delivery in twin pregnancies. All the patients had a transvaginal ultrasound scan for cervical length at 24 weeks, followed by a high vaginal swab for IGFBP-1 at 26 weeks. A total of 95% of women screened negative for the IGFBP-1 test. None of these women delivered before 30 weeks; 7.50% delivered between 30 and 33+6 weeks; 87.5% delivered after 34 weeks. Two women (5.00%) screened positive for phosphorylated insulin-like growth factor binding protein-1; one had a spontaneous pre-term delivery at 30 weeks, while the other patient delivered at 38 weeks. It was concluded that women with twin pregnancies that have negative phosphorylated insulin-like growth factor binding protein-1 have a low risk of delivery before 34 weeks in the absence of other obstetric complications.

Transvaginal cervical length measurement for prediction of preterm birth in women with threatened preterm labor: a meta-analysis

OBJECTIVES

To integrate data on the performance of cervical length measurement for the prediction of preterm birth in symptomatic women.

METHODS

MEDLINE, SCOPUS and manual searches for studies with transvaginal ultrasound measurement of the cervical length in symptomatic women were carried out. Random effects models were used for data integration, and pooled test estimates of sensitivity, specificity, and positive and negative likelihood ratios (LR+ and LR-) were calculated along with their 95% CIs.

RESULTS

Twenty-eight studies fulfilled the selection criteria. For birth within 1 week from presentation, the pooled sensitivity, specificity, LR+ and LR- of cervical length < 15 mm were 59.9% (95% CI, 52.7-66.8%), 90.5% (95% CI, 89.0-91.9%), 5.71 (95% CI, 3.77-8.65) and 0.51 (95% CI, 0.33-0.80), respectively. The same estimates for studies with presentation at or before 34 + 0 weeks were 71.0% (95% CI, 60.6-79.9%), 89.8% (95% CI, 87.4-91.9%), 5.19 (95% CI, 2.29-11.74) and 0.38 (95% CI, 0.11-1.34), respectively. For prediction of birth before 34 weeks, the pooled sensitivity, specificity, LR+ and LR- of cervical length < 15 mm were 46.2% (95% CI, 34.8-57.8%), 93.7% (95% CI, 90.7-96.0%), 4.31 (95% CI, 2.73-6.82) and 0.63 (95% CI, 0.38-1.04), respectively. There was considerable heterogeneity across studies in most estimates.

CONCLUSIONS

Measurement of cervical length in symptomatic women can detect a significant proportion of those who will deliver within 1 week and help to rationalize their management. The considerable heterogeneity across studies may be indicative of methodological flaws, which either were not reported at all or were under-reported.

Phosphorylated insulin-like growth factor binding protein-1 in cervical secretions and sonographic cervical length in the prediction of spontaneous preterm delivery

OBJECTIVES

The aim of this study was to evaluate the efficacy of the test for the decidual phosphorylated isoform of insulin-like growth factor binding protein-1 (phIGFBP-1) in endocervical secretions in predicting preterm delivery in women with uterine contractions.

METHODS

The study included 210 women with a singleton pregnancy with documented uterine contractions and intact membranes at between 24 and 34 weeks' gestation who underwent the cervicovaginal phIGFBP-1 test and transvaginal sonographic measurement of cervical length. A receiver-operating characteristics (ROC) curve was used to determine the most useful cut-off point for cervical length. A multivariate logistic regression model was used in order to analyze the combination of significant predictive variables for preterm delivery following univariate analysis.

RESULTS

ROC curves indicated that 26 mm was the optimal cut-off value for cervical length in predicting preterm delivery. A cervical length of < 26 mm and the presence of phIGFBP-1 were statistically significant in univariate logistic regression analyses (P < 0.0001) with odds ratios of 16.18 and 9.29 for preterm delivery, respectively. Multivariate analysis of cervical length and phIGFBP-1 showed that they were independent and therefore useful in combination for predicting preterm delivery.

CONCLUSIONS

Cervical length and the phIGFBP-1 test are independent variables that can be used together to predict preterm delivery in women with uterine contractions. A sonographically measured cervical length of > 26 mm with a negative phIGFBP-1 test in a patient with regular uterine contractions before 37 weeks' gestation seems to indicate a low risk of preterm delivery and may therefore allow avoidance of unnecessary therapies.

Insulin-like growth factor-binding protein-1 (IGFBP-1) in cervical secretions as a predictor of preterm delivery

OBJECTIVE

The objective of this study was to investigate the level of insulin-like growth factor-binding protein-1 (IGFBP-1) in cervical secretions and Bishop score as predictors of preterm delivery in asymptomatic pregnant women.

METHODS

This was a prospective study at the Clinic for Gynecology and Obstetrics at the University Clinical Center in Tuzla, on a sample of 80 healthy pregnant women at between 24 and 34 gestational weeks. After interview every woman underwent IGFBP-1 concentration measurement by the 'Actim Partus' test. The Bishop score was determined by the author (A.L) during vaginal examination. Rates among groups were compared using arithmetic mean and standard deviation, Student's t-test, Mann-Witney U-test, and Spearman-Rank correlation test. Statistical importance was determined at the variation levels of 5% and 1%.

RESULTS

Eight (10.00%) women in the study group had a positive Actim Partus test and six (7.50%) of them had a preterm delivery. The positive predictive value was 44.44% and negative predictive value was 98.59%. The specificity of the Bishop score in the study group was 83.78% and the sensitivity was 50.00%. The positive predictive value of the Bishop score in this group was 20.00% and the negative predictive value was 95.36%. There was no correlation between the Bishop score and Actim Partus test (p = 0.15).

CONCLUSIONS

If the concentration of IGFBP-1 is <10 microg/L (negative Actim Partus test) in asymptomatic pregnant women, the risk of preterm delivery is low. The Actim Partus test could be used as a screening test for preterm delivery in asymptomatic pregnant women.

Cervical phosphorylated insulin-like growth factor binding protein-1 in prediction of preterm delivery

BACKGROUND

The aim of this study was to evaluate the phosphorylated isoform of insulin-like growth factor binding protein-1 (phIGFBP-1) in endocervical secretions as a predictor of preterm delivery in symptomatic and asymptomatic pregnant women.

METHODS

The study included 105 patients between 24 and 34 weeks' gestation with uterine contractions and 73 controls. Ph IGFBP-1 in cervical secretions was assessed in all patients by using a qualitative, immunochromatographic one-step dipstick test. Data analysis included Student's test, Chi-Square, Fisher's exact test and Kruskal Wallis variance analysis.

RESULTS

Preterm birth rate was 19.04% (20/105) in the study group. Of the 25 patients with a positive phIGFBP-1 test, mean gestational age at delivery was 32.8+/-3.8, whereas of the 80 patients with a negative phIGFBP-1 test mean gestational age at delivery was 37.8+/-2.5, in the study group (P<0.05). The sensitivity, specificity, positive predictive value and negative predictive value for phIGFBP-1 in symptomatic patients were 70, 87.05, 56 and 92.5%, respectively, while in asymptomatic patients they were 40, 82.35, 14.28 and 94.91%, respectively.

CONCLUSIONS

The phIGFBP-1 in cervical secretions is a potential specific marker for preterm delivery occurring before 37 weeks. Also cervical detection of phIGFBP-1 by immunochromatography is a rapid and easily applicable test that highly predicts preterm delivery.