Screening to prevent spontaneous preterm birth: systematic reviews of accuracy and effectiveness literature with economic modelling

Cervical length screening among low-risk women; relationship of body mass index on cervical length and risk of preterm birth

BACKGROUND

Preterm birth (PTB) contributes to nearly 11% of all deliveries in the world. The majority of spontaneous preterm birth (sPTB) remains unexplained. Risk factors include abnormal body mass index (BMI), short cervical length, comorbidities and many more. However, there is limited study on the association between body mass index, cervical length and preterm birth in Malaysia among low-risk women. Hence, we aim to examine the relationship between body mass index, cervical length and the risk of spontaneous preterm birth.

METHOD

In this prospective cohort study, pregnant women between 16 and 24 weeks who fulfilled the criteria were recruited. Women with history of preterm birth were excluded. Demographic and clinical data (age, BMI, ethnicity, education level and parity) were obtained. Cervical length was measured using transvaginal scan. Patients were then followed up till delivery to determine their delivery gestation and outcome of delivery.

RESULTS

Out of 153 women who participated in this study, 146 women had cervical length of more than 30 mm, six had cervical length between 25 mm and 30 mm and one had cervical length of 24 mm. There were nine (9) cases of sPTB, with all of them being late preterm with normal midtrimester cervical length. Almost half of them (44%) were overweight/obese. A significant association was found between age, cervical length, and parity compared to BMI. Nevertheless, no significant association was seen between the BMI and risk of sPTB.

CONCLUSION

This study demonstrates a higher BMI is associated with longer cervical length, but it is not necessarily protective against sPTB. Hence, we concluded there is a limited role in cervical length screening among low-risk women regardless of their BMI in predicting sPTB.

Evaluating the Efficacy of Cervical Tactile Ultrasound Technique as a Predictive Tool for Spontaneous Preterm Birth

Background

Premature cervical softening and shortening may be considered an early mechanical failure that predispose to preterm birth.

Purpose

This study aims to explore the applicability of an innovative cervical tactile ultrasound approach for predicting spontaneous preterm birth (sPTB).

Materials and Methods

Eligible participants were women with low-risk singleton pregnancies in their second trimester, enrolled in this prospective observational study. A Cervix Monitor (CM) device was designed with a vaginal probe comprising four tactile sensors and a single ultrasound transducer operating at 5 MHz. The probe enabled the application of controllable pressure to the external cervical surface, facilitating the acquisition of stress-strain data from both anterior and posterior cervical sectors. Gestational age at delivery was recorded and compared against cervical elasticity.

Results

CM examination data were analyzed for 127 women at 240/7 - 286/7 gestational weeks. sPTB was observed in 6.3% of the cases. The preterm group exhibited a lower average cervical stress-to-strain ratio (elasticity) of 0.70 ± 0.26 kPa/mm compared to the term group's 1.63 ± 0.65 kPa/mm with a p-value of 1.1 × 10-4. Diagnostic accuracy for predicting spontaneous preterm birth based solely on cervical elasticity data was found to be 95.0% (95% CI, 88.5 - 100.0).

Conclusion

These findings suggest that measuring cervical elasticity with the designed tactile ultrasound probe has the potential to predict spontaneous preterm birth in a cost-effective manner.

Microbiome preterm birth DREAM challenge: Crowdsourcing machine learning approaches to advance preterm birth research

Every year, 11% of infants are born preterm with significant health consequences, with the vaginal microbiome a risk factor for preterm birth. We crowdsource models to predict (1) preterm birth (PTB; <37 weeks) or (2) early preterm birth (ePTB; <32 weeks) from 9 vaginal microbiome studies representing 3,578 samples from 1,268 pregnant individuals, aggregated from public raw data via phylogenetic harmonization. The predictive models are validated on two independent unpublished datasets representing 331 samples from 148 pregnant individuals. The top-performing models (among 148 and 121 submissions from 318 teams) achieve area under the receiver operator characteristic (AUROC) curve scores of 0.69 and 0.87 predicting PTB and ePTB, respectively. Alpha diversity, VALENCIA community state types, and composition are important features in the top-performing models, most of which are tree-based methods. This work is a model for translation of microbiome data into clinically relevant predictive models and to better understand preterm birth.

Predicting preterm birth using machine learning techniques in oral microbiome

Preterm birth prediction is essential for improving neonatal outcomes. While many machine learning techniques have been applied to predict preterm birth using health records, inflammatory markers, and vaginal microbiome data, the role of prenatal oral microbiome remains unclear. This study aimed to compare oral microbiome compositions between a preterm and a full-term birth group, identify oral microbiome associated with preterm birth, and develop a preterm birth prediction model using machine learning of oral microbiome compositions. Participants included singleton pregnant women admitted to Jeonbuk National University Hospital between 2019 and 2021. Subjects were divided into a preterm and a full-term birth group based on pregnancy outcomes. Oral microbiome samples were collected using mouthwash within 24 h before delivery and 16S ribosomal RNA sequencing was performed to analyze taxonomy. Differentially abundant taxa were identified using DESeq2. A random forest classifier was applied to predict preterm birth based on the oral microbiome. A total of 59 women participated in this study, with 30 in the preterm birth group and 29 in the full-term birth group. There was no significant difference in maternal clinical characteristics between the preterm and the full-birth group. Twenty-five differentially abundant taxa were identified, including 22 full-term birth-enriched taxa and 3 preterm birth-enriched taxa. The random forest classifier achieved high balanced accuracies (0.765 ± 0.071) using the 9 most important taxa. Our study identified 25 differentially abundant taxa that could differentiate preterm and full-term birth groups. A preterm birth prediction model was developed using machine learning of oral microbiome compositions in mouthwash samples. Findings of this study suggest the potential of using oral microbiome for predicting preterm birth. Further multi-center and larger studies are required to validate our results before clinical applications.

Diagnosis or prognosis? An umbrella review of mid-trimester cervical length and spontaneous preterm birth

BACKGROUND

Cervical length is widely used to assess a woman's risk of spontaneous preterm birth (SPTB).

OBJECTIVES

To summarise and critically appraise the evidence from systematic reviews on the prognostic capacity of transvaginal sonographic cervical length in the second trimester in asymptomatic women with singleton or twin pregnancy.

SEARCH STRATEGY

Searches were performed in Medline, Embase, CINAHL and grey literature from 1 January 1995 to 6 July 2021, including keywords 'cervical length', 'preterm birth', 'obstetric labour, premature', 'review' and others, without language restriction.

SELECTION CRITERIA

We included systematic reviews including women who did not receive treatments to reduce SPTB risk.

DATA COLLECTION AND ANALYSIS

From 2472 articles, 14 systematic reviews were included. Summary statistics were independently extracted by two reviewers, tabulated and analysed descriptively. The ROBIS tool was used to evaluate risk of bias of included systematic reviews.

MAIN RESULTS

Twelve reviews performed meta-analyses: two were reported as systematic reviews of prognostic factor studies, ten used diagnostic test accuracy methodology. Ten systematic reviews were at high or unclear risk of bias. Meta-analyses reported up to 80 combinations of cervical length, gestational age at measurement and definition of preterm birth. Cervical length was consistently associated with SPTB, with a likelihood ratio for a positive test of 1.70-142.

CONCLUSIONS

The ability of cervical length to predict SPTB is a prognostic research question; systematic reviews typically analysed diagnostic test accuracy. Individual participant data meta-analysis using prognostic factor research methods is recommended to better quantify how well transvaginal ultrasonographic cervical length can predict SPTB.

CERVICITIS AS A CAUSE OF PRETERM BIRTH IN WOMEN

OBJECTIVE

The aim: To evaluate the prevalence of preterm birth and to determine the role of cervicitis as a cause of preterm birth in women in Ukraine.

PATIENTS AND METHODS

Materials and methods: We conducted a retrospective multicentre cohort study from January 1st, 2019 to December 31st, 2021. This study included pregnant women aged 17-50 years admitted to the labor ward at the 13 hospitals from 10 regions of Ukraine.

RESULTS

Results: Of the 8151 participants, the prevalence of preterm birth was 2226 (27.3%, [95% CI 26.8 - 27.8]) whereas 5925 (72.7% [95% CI 72.2-73.2]) delivered at term. Preterm birth associated with cervicitis was 76.3% (4,388/2666). History of cervicitis, maternal age, previous preterm labor or premature birth, and pregnancy with twins, triplets or other multiples were identified as independent risk factors of preterm birth.

CONCLUSION

Conclusions: Preterm birth in Ukraine is widespread, the number of which tends to increase. Infection and inflammation of the cervix seem to play a significant role for preterm birth. Early detection and treatment of cervicitis can reduce the risk of preterm birth. Women who have a history of poor pregnancy outcomes are at greater risk of poor outcomes in following pregnancies. Health providers should be aware of this risk when treating patients with a history of poor pregnancy outcomes.

Emotional regulation and psychomotor development after threatening preterm labor: a prospective study

A threatened preterm labor (TPL) represents an adverse prenatal event that may affect fetal neurodevelopment, even in absence of prematurity. Indeed, late-preterm infants, without neurological complications, also exhibit neurodevelopment impairment with psychomotor delay as well as emotional regulation disturbances, considered early manifestations of neuropsychiatric disorders. The aim of this study is to examine the impact of TPL on infant's psychomotor development and temperament. This prospective cohort study recruited mothers who suffered from a TPL and a control group of mothers without TPL and full-term gestation (n = 61). TPL infants were classified into three groups depending on delivery time: Full-Term (n = 37), Late-Preterm (n = 66), and Very-Preterm (n = 38). Neurodevelopmental assessment was performed at 6 months using the Ages & Stages Questionnaires for psychomotor development and the Infant Behaviour Questionnaire-Revised for temperament. After controlling for potential cofounders (multiple pregnancy and in vitro fertilization), Full-Term TPL infants, relative to the control group, exhibited development delay in Communication (p = 0.044) and Personal-social domains (p = 0.005) as well as temperament disturbances with higher Negative Affect (p = 0.013), lower Positive Affect (p = 0.010), and worse Emotional Regulation (p < 0.001) compared to Control. No differences were found between Full-Term and Late-Preterm TPL infants. TPL may represent a risk factor for neurodevelopmental disturbances in the offspring, affecting both psychomotor and emotional infant competences, even when infants were born at term.

Predictive Models for Very Preterm Birth: Developing a Point-of-Care Tool

OBJECTIVE

The objective of this study was to create three point-of-care predictive models for very preterm birth using variables available at three different time points: prior to pregnancy, at the end of the first trimester, and mid-pregnancy.

STUDY DESIGN

This is a retrospective cohort study of 359,396 Ohio Medicaid mothers from 2008 to 2015. The last baby for each mother was included in the final dataset. Births prior to 22 weeks were excluded. Multivariable logistic regression was used to create three models. These models were validated on a cohort that was set aside and not part of the model development. The main outcome measure was birth prior to 32 weeks.

RESULTS

The final dataset contained 359,396 live births with 6,516 (1.81%) very preterm births. All models had excellent calibration. Goodness-of-fit tests suggested strong agreement between the probabilities estimated by the model and the actual outcome experience in the data. The mid-pregnancy model had acceptable discrimination with an area under the receiver operator characteristic curve of approximately 0.75 in both the developmental and validation datasets.

CONCLUSION

Using data from a large Ohio Medicaid cohort we developed point-of-care predictive models that could be used before pregnancy, after the first trimester, and in mid-pregnancy to estimate the probability of very preterm birth. Future work is needed to determine how the calculator could be used to target interventions to prevent very preterm birth.

KEY POINTS

· We developed predictive models for very preterm birth.. · All models showed excellent calibration.. · The models were integrated into a risk calculator..

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.

Using quantitative fetal fibronectin to predict term labour onset in Australian rural women: A pilot study

BACKGROUND

Many women living in rural and remote Australia are required to travel large distances to birth in a hospital with maternity facilities, incurring considerable financial, social and emotional burden for them and their families. No studies to date have investigated the use of quantitative fetal fibronectin (qfFN) to predict term labour in asymptomatic pregnant women. A tool which is able to more accurately predict term labour has the potential to guide informed travel decision-making for women and healthcare professionals in rural and remote Australia.

AIM

The aim of this study is to determine if qfFN can reliably predict term labour in asymptomatic women from rural and remote areas.

MATERIALS AND METHODS

Thirty-nine women from rural Australia provided 71 fFN samples between June 2016 and October 2018, from 37 weeks' gestation, with at least one week between samples for those providing multiple samples. Days from fFN sampling until spontaneous onset of labour were recorded. Using generalised estimating equation modelling we examined the utility of fFN as a predictor for onset of labour at term after adjusting for confounders.

RESULTS

There was a small-to-moderate negative correlation (r_s -0.27, P < 0.05) between time until labour and fFN. Quantitative fFN was observed to be a significant predictor of time until labour after adjusting for confounding variables (P < 0.001).

CONCLUSION

fFN levels may play a role in predicting term labour in rural women; however, future studies with a larger sample size are required to validate the findings of our pilot study.

The amniotic fluid cell-free transcriptome in spontaneous preterm labor

The amniotic fluid (AF) cell-free RNA was shown to reflect physiological and pathological processes in pregnancy, but its value in the prediction of spontaneous preterm delivery is unknown. Herein we profiled cell-free RNA in AF samples collected from women who underwent transabdominal amniocentesis after an episode of spontaneous preterm labor and subsequently delivered within 24 h (n = 10) or later (n = 28) in gestation. Expression of known placental single-cell RNA-Seq signatures was quantified in AF cell-free RNA and compared between the groups. Random forest models were applied to predict time-to-delivery after amniocentesis. There were 2385 genes differentially expressed in AF samples of women who delivered within 24 h of amniocentesis compared to gestational age-matched samples from women who delivered after 24 h of amniocentesis. Genes with cell-free RNA changes were associated with immune and inflammatory processes related to the onset of labor, and the expression of placental single-cell RNA-Seq signatures of immune cells was increased with imminent delivery. AF transcriptomic prediction models captured these effects and predicted delivery within 24 h of amniocentesis (AUROC = 0.81). These results may inform the development of biomarkers for spontaneous preterm birth.

Measurement of the uterocervical angle for the prediction of preterm birth in symptomatic women

Purpose

To examine if the uterocervical angle (UCA) can be used to predict preterm delivery in women with painful and regular uterine contractions and a cervical length of 25 mm or less.

Methods

Retrospective study at the perinatal unit of the University Hospital of Tuebingen, Germany. Women with singleton gestation and preterm contractions between 24 + 0 and 33 + 6 weeks’ gestation were included. For the UCA measurement, a line is placed from the internal os to the external os irrespective of whether the cervix is straight or curved. A second line is drawn to delineate the lower uterine segment. The angle between the two lines is the UCA measurement. The measurements were taken on stored images from our database.

Results

The study consisted of 213 singleton pregnancies. At the time of UCA measurement, median maternal and gestational age was 31.4 years and 29.7 weeks’ gestation. Median gestational age at delivery was 35.3 weeks and the corresponding birth weight 2480 g, respectively. The UCA measurement in women who delivered within 2 days, between 3–7 days and after 7 days was not helpful to distinguish between these three groups [median UCA measurements: 108.5°, 108.0° and 107.3° (Kruskal–Wallis test p = 0.576)]. Uni- and multivariate logistic multiple regression analysis demonstrated that the delivery within 2 days was only dependent on the gestational age and the cervical length at the time of presentation.

Conclusion

The measurement of UCA is not useful in predicting preterm birth in the subsequent 7 days after an episode of preterm contractions.

Methods of detection and prevention of preterm labour and the PAMG-1 detection test: a review

OBJECTIVES

Preterm labour is the leading cause of hospitalization during pregnancy. In France, it results in more than 60,000 births before 37 weeks of gestation every year. Recent studies suggest that detection of placental α-microglobulin-1 (PAMG-1) in vaginal secretions among women presenting symptoms of preterm labour with intact membranes has good predictive value for the onset of spontaneous preterm delivery within 7 days. The test is especially interesting, in that the repetition of antenatal corticosteroids for foetal lung maturation is no longer recommended in France and the effect of the initial administration is most beneficial in the 24 h to 7 days afterwards.

METHODS

We included all studies listed in PubMed and clinicaltrials.gov with the terms "PAMG-1" and either "preterm labor" or "preterm labour", while excluding all studies on the subject of "rupture of the membranes" from 2000 through 2017. Ten studies were thus included.

RESULTS

In women who had both the PAMG-1 and foetal fibronectin test, the PAMG-1 test was statistically superior to the measurement of cervical length for positive predictive value (p<0.0074), negative predictive value (p=0.0169) and specificity (p<0.001) for the prediction of spontaneous preterm delivery within 7 days.

CONCLUSIONS

The use of PAMG-1 may make it possible to target the women at risk with a shortened cervix on ultrasound (<25 mm) those with an imminent preterm delivery and therefore to adapt management, especially the administration of antenatal corticosteroid therapy.

Prediction of preterm birth: the role cervical assessment by ultrasound and cervico-vaginal biomarkers

Preterm delivery (PTB) is one of the most common and serious complications of pregnancy. PTB accounts for approximately 70% of neonatal deaths and is a major cause of neonatal morbidity including respiratory distress syndrome, necrotising enterocolitis and long-term neurological disabilities. Prevention of PTB and its complications include identification among symptomatic women those at high risk of immediate delivery requiring prenatal corticosteroids administration. Transvaginal ultrasonographic evaluation of the cervical length (CL) is predictive of PTB and a value 15 mm identifies among symptomatic women approximately 70% of women who will deliver within one week. In the range of CL within 15 and 30 mm biomarkers n cervical-vaginal fluids (fetal fibronectin, phosphorylated insulin-like growth factor protein-1, placental alpha-microglobulin-, cytokines) and other ultrasonographic cervical variables (posterior cervical angle, elastography) improve the identification of women at risk, In asymptomatic women CL can be applied as screening and has been proposed as a universal screening during the second trimester in singleton gestations. The finding of a CL25mm is associated with an increased risk of subsequent PTB with a sensitivity between 30 and 60% that is improved with the combination of biomarkers. Asymptomatic women with a CL 25mm should be offered vaginal progesterone treatment for the prevention of preterm birth and neonatal morbidity. The role of cerclage and pessary is still controversial. In this review we discuss the evidence-based role of ultrasonographic cervical assessment and cervicovaginal biomarkers in the prediction of PTB in symptomatic and asymptomatic women

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.

Progesterone and preterm birth

Progestogens (vaginal progesterone and intramuscular 17-hydroxyprogesterone acetate) are widely recommended for women at high risk of preterm birth. Typical regimens include 17-hydroxyprogesterone caproate (250 mg intramuscularly weekly), starting at 16-20 gestational weeks until 36 weeks or delivery for women with a singleton gestation and a history of spontaneous preterm birth, or vaginal progesterone (90-mg vaginal gel or 200-mg micronized vaginal soft capsules) for women with a short cervix (typically ≤25 mm). Although some randomized trials support this approach, neither of the largest trials (PROLONG for 17-hydroxyprogesterone acetate or OPPTIMUM for vaginal progesterone) demonstrated efficacy. There are almost no data on long-term effects, and none that shows benefit beyond the neonatal period. Although some analyses suggest the cost-effectiveness of the approach, a cervical length screening program followed by progesterone for those with a short cervix will reduce preterm birth rates by less than 0.5%. The present review assesses evidence on the efficacy, likely impact, and long-term effects of implementing the recommendations for progestogens in full. Clinicians and pregnant women can look forward to resolution of the conflicting views on efficacy once the Patient-Centered Outcomes Research Initiative (PCORI)-funded individual patient data meta-analysis is published.

Preference-Based Health-Related Quality of Life Outcomes Associated with Preterm Birth: A Systematic Review and Meta-analysis

OBJECTIVES

Assessments of health-related quality of life outcomes associated with preterm birth provide valuable complementary data to the objective biomedical assessments that have traditionally been reported. The objective of this study was to perform a systematic review and meta-analysis of health utility values associated with preterm birth generated using preference-based approaches to health-related quality of life measurement.

METHODS

Systematic searches of MEDLINE, Web of Science, EconLit, EMBASE, CINAHL, PsycINFO, the Cochrane Library and SCOPUS were performed, covering the literature from inception of the search engines to 26 June 2018. Studies reporting health utility values estimated using either direct or indirect utility elicitation methods and published in the English language were included. Central descriptive statistics and measures of variability surrounding health utility values for each study and control group, and differences between comparator groups, are reported for each included article. The effect of preterm birth on health utility values was estimated using a hierarchical linear model in a linear mixed-effects meta-regression.

RESULTS

Of 2139 unique articles retrieved, 20 articles met the inclusion criteria. All but one study used the Health Utilities Index (HUI) Mark 2 (HUI2) or Mark 3 (HUI3) measures as their primary health utility assessment method. All studies reporting health utility values for individuals born preterm or at low birthweight and a control group of individuals born at full term or normal birthweight reported lower utility values in the study groups, regardless of age at assessment, respondent type or valuation method. The meta-regression revealed that preterm birth was associated with a mean utility decrement of 0.066 (95% confidence interval [CI] 0.035-0.098; p < 0.001) after controlling for valuation method, respondent type, administration mode, year of publication, geographical region of study, study setting and age at assessment.

CONCLUSION

Evidence identified by this review can act as data inputs into future economic evaluations of preventive or treatment interventions for preterm birth. Future research should focus particularly on estimating health utility values during the various stages of adulthood, and incorporating the effects of preterm birth on the preference-based health-related quality of life outcomes of parents and other family members.

Single and repeat cervical-length measurement in twin gestation with threatened preterm labor

OBJECTIVE

To examine the effectiveness of single and repeat sonographic cervical-length (CL) measurement in predicting preterm delivery in symptomatic women with a twin pregnancy.

METHODS

This was a retrospective study of women with a twin gestation who presented with painful and regular uterine contractions at 24 + 0 to 33 + 6 weeks' gestation at the perinatal unit of the University Hospital of Tübingen, Tübingen, Germany between 2012 and 2018. CL was measured on transvaginal ultrasound at the time of admission and a few days later after cessation of contractions. Treatment included administration of tocolytics (usually oral nifedipine), for no more than 48 h, and administration of steroids if CL was ≤ 25 mm. Patients were clustered into five groups according to the CL measurement obtained at first assessment: < 10.0 mm; between 10.0 and 14.9 mm; between 15.0 and 19.9 mm; between 20.0 and 24.9 mm; and ≥ 25.0 mm. For each group, we calculated the test performance of CL measurement for prediction of preterm delivery within the subsequent 7 days and before 34 weeks' gestation. Regression analysis was used to evaluate the test performance of the second CL measurement for predicting preterm delivery within 7 days after the second assessment.

RESULTS

The study population consisted of 257 twin pregnancies, of which 80.2% were dichorionic diamniotic. Median maternal and gestational ages at the time of admission were 32.0 years and 29.9 weeks' gestation, respectively. Preterm birth within 7 days of admission occurred in 23 (8.9%) pregnancies, and 82 (31.9%) patients delivered prior to 34 weeks' gestation. Median CL for the entire study population was 17.0 mm. Delivery within 7 days after the first assessment occurred in 29.0%, 10.6%, 4.2%, 6.3% and 0% of women with CL < 10.0 mm, 10.0-14.9 mm, 15.0-19.9 mm, 20.0-24.9 mm and ≥ 25.0 mm, respectively. There was a weak, but significant, association between the CL measurement at the time of admission and the time interval between admission and delivery (interval = 27.9 + 0.58 × CL; P = 0.003, r = 0.184). CL was measured again after a median time interval of 3 (interquartile range (IQR), 2-5) days in 248 cases. Median second CL measurement was 17.0 (IQR, 11.5-22.0) mm. Delivery occurred within the subsequent 7 days after the second measurement in 25/248 (10.1%) cases. Binary regression analysis indicated that the first (odds ratio (OR), 0.895; P = 0.003) and second (OR, 0.908; P = 0.002) CL measurements, but not the difference between the two measurements (OR, 0.961; P = 0.361), were associated significantly with delivery within 7 days after the second measurement. Receiver-operating-characteristics (ROC)-curve analysis for the prediction of delivery within 7 days after the second assessment did not show a significant difference between the predictive performance of the first (area under ROC curve (AUC), 0.676 (95% CI, 0.559-0.793)) and the second (AUC, 0.661 (95% CI, 0.531-0.790)) measurement.

CONCLUSION

Sonographic measurement of CL can be helpful in predicting preterm delivery within 7 days of presentation in symptomatic women with a twin gestation; however, the test performance is relatively weak. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Combined insulin-like growth factor binding protein-1/interleukin-6 (Premaquick) versus fetal fibronectin for predicting preterm delivery among women with preterm contractions

OBJECTIVES

To compare accuracy between Premaquick (combined test for native insulin-like growth factor binding protein-1 (IGFBP-1), total IGFBP-1, and interleukin-6) and fetal fibronectin (Ffn) in predicting preterm delivery.

METHODS

Prospective study among women at 28-36⁺⁶ gestational weeks with threatened preterm labor attending Federal Medical Center, Owerri, Nigeria, from August 2017 to February 2019. Cervico-vaginal fluids were collected and tested by Premaquick and Ffn tests. The women were followed for 14 days. Sensitivity, specificity, and negative (NPV) and positive (PPV) predictive value for delivery were compared between the tests.

RESULTS

Among 213 women assessed for eligibility, 183 were enrolled and 175 completed the study. The sensitivity, specificity, PPV, NPV, and accuracy of the Premaquick versus Ffn tests were, respectively, 96.3% versus 51.9%, 97.6% versus 98.4%, 89.7% versus 87.5%, 99.2% versus 90.3% and 97.3% versus 90.0% for preterm delivery within 14 days. Ffn had higher specificity (98.5% vs 97.8%; P>0.99), but Premaquick had higher PPV (92.7% vs 90.9%; P>0.99).

CONCLUSION

Both tests seem to have high utility in predicting preterm delivery, but Premaquick showed higher accuracy in terms of sensitivity and PPV. Premaquick might be a feasible alternative to Ffn for predicting preterm delivery among symptomatic women in a low-income setting.

Cervical Characterization with Tactile-Ultrasound Probe

BACKGROUND

Premature cervical softening and shortening may be considered an early mechanical failure that predisposes to preterm birth. Preliminary clinical studies demonstrate that cervical elastography may be able to quantify this phenomenon and predict spontaneous preterm delivery.

OBJECTIVE

To explore a new approach for cervix elasticity and length measurements with tactile-ultrasound probe.

METHODS

Cervix probe has tactile array and ultrasound transducer designed to apply controllable load to cervix and acquire stress-strain data for calculation of cervical elasticity (Young's modulus) and cervical length for four cervix sectors. Average values, standard deviations, intraclass correlation coefficients and the 95% limits of agreement (Bland-Altman plots) were estimated.

RESULTS

Ten non-pregnant and ten pregnant women were examined with the probe. The study with non-pregnant women demonstrated a reliable acquisition of the tactile signals. The ultrasound signals had a prolonged appearance; identification of the internal os of the cervix in these signals was not reliable. The study with pregnant women with the gestational age of 25.4 ± 2.3 weeks demonstrated reliable data acquisition with real-time visualization of the ultrasound signals. Average values for cervical elasticity and standard deviations of 19.7 ± 15.4 kPa and length of 30.7 ± 6.6 mm were calculated based on two measurements per 4 sectors. Measurement repeatability calculated as intraclass correlation coefficients between two measurements at the same cervix sector on pregnant women was found to be 0.97 for cervical elasticity and 0.93 for the cervical length. The 95% limits of agreement of 1) cervical elasticity were from -22.4% to +14.9%, and 2) cervical length from -13.3% to +16.5%.

CONCLUSIONS

This study demonstrated clinically acceptable measurement performance and reproducibility. The availability of stress-strain data allowed the computation of cervical elasticity and length. This approach has the potential to provide cervical markers to predict spontaneous preterm delivery.

Antibiotics for asymptomatic bacteriuria in pregnancy

BACKGROUND

Asymptomatic bacteriuria is a bacterial infection of the urine without any of the typical symptoms that are associated with a urinary infection, and occurs in 2% to 15% of pregnancies. If left untreated, up to 30% of mothers will develop acute pyelonephritis. Asymptomatic bacteriuria has been associated with low birthweight and preterm birth. This is an update of a review last published in 2015.

OBJECTIVES

To assess the effect of antibiotic treatment for asymptomatic bacteriuria on the development of pyelonephritis and the risk of low birthweight and preterm birth.

SEARCH METHODS

For this update, we searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) on 4 November 2018, and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCT) comparing antibiotic treatment with placebo or no treatment in pregnant women with asymptomatic bacteriuria found on antenatal screening. Trials using a cluster-RCT design and quasi-RCTs were eligible for inclusion, as were trials published in abstract or letter form, but cross-over studies were not.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data, and checked for accuracy. We assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

We included 15 studies, involving over 2000 women. Antibiotic treatment compared with placebo or no treatment may reduce the incidence of pyelonephritis (average risk ratio (RR) 0.24, 95% confidence interval (CI) 0.13 to 0.41; 12 studies, 2017 women; low-certainty evidence). Antibiotic treatment may be associated with a reduction in the incidence of preterm birth (RR 0.34, 95% CI 0.13 to 0.88; 3 studies, 327 women; low-certainty evidence), and low birthweight babies (average RR 0.64, 95% CI 0.45 to 0.93; 6 studies, 1437 babies; low-certainty evidence). There may be a reduction in persistent bacteriuria at the time of delivery (average RR 0.30, 95% CI 0.18 to 0.53; 4 studies; 596 women), but the results were inconclusive for serious adverse neonatal outcomes (average RR 0.64, 95% CI 0.23 to 1.79, 3 studies; 549 babies). There were very limited data on which to estimate the effect of antibiotics on other infant outcomes, and maternal adverse effects were rarely described. Overall, we judged only one trial at low risk of bias across all domains; the other 14 studies were assessed as high or unclear risk of bias. Many studies lacked an adequate description of methods, and we could only judge the risk of bias as unclear, but in most studies, we assessed at least one domain at high risk of bias. We assessed the quality of the evidence for the three primary outcomes with GRADE software, and found low-certainty evidence for pyelonephritis, preterm birth, and birthweight less than 2500 g.

AUTHORS' CONCLUSIONS

Antibiotic treatment may be effective in reducing the risk of pyelonephritis in pregnancy, but our confidence in the effect estimate is limited given the low certainty of the evidence. There may be a reduction in preterm birth and low birthweight with antibiotic treatment, consistent with theories about the role of infection in adverse pregnancy outcomes, but again, the confidence in the effect is limited given the low certainty of the evidence. Research implications identified in this review include the need for an up-to-date cost-effectiveness evaluation of diagnostic algorithms, and more evidence to learn whether there is a low-risk group of women who are unlikely to benefit from treatment of asymptomatic bacteriuria.

The risk of spontaneous preterm birth in asymptomatic women with a short cervix (≤25 mm) at 23-28 weeks' gestation

BACKGROUND

Asymptomatic short cervical length is an independent risk factor for spontaneous preterm birth. However, most studies have focused on the associated risk of a short cervical length when encountered between 16 and 23 weeks' gestation. The relationship between cervical length and risk of spontaneous preterm birth after 23 weeks is not well known.

OBJECTIVE

To evaluate the risk of spontaneous preterm birth in asymptomatic women with a short cervix (≤25 mm) at 23-28 weeks' gestation.

MATERIALS AND METHODS

A retrospective cohort study of women with asymptomatic short cervix (cervical length ≤25 mm) at extreme prematurity, defined as 23-28 weeks' gestation, was performed at a single center from January 2015 to March 2018. Women with symptoms of preterm labor, multiple gestations, fetal or uterine anomalies, cervical cerclage, or those with incomplete data were excluded from the study. Demographic information as well as data on risk factors for spontaneous preterm birth were collected. Patients were divided into 4 groups based on the cervical length measurement (≤10 mm, 11-15 mm, 16-20 mm, and 21-25 mm). The primary outcome was time interval from enrollment to delivery. Secondary outcomes included delivery within 1 and 2 weeks of enrollment, gestational age at delivery, and delivery prior to 32, 34, and 37 weeks, respectively. Continuous variables were compared using Kruskal-Wallis test, whereas categorical variables were compared using the χ² or Fisher exact test as appropriate. The Wilcoxon test for difference in survival time was used to compare gestational age at delivery among the 4 cervical length groups, with data stratified based on gestational age at enrollment.

RESULTS

Of the 126 pregnancies that met inclusion criteria, 22 (17.4%) had a cervical length of ≤10 mm, 23 (18.3%) had a cervical length of 11-15 mm, 37 (29.4%) had a cervical length of 16-20 mm, and 44 (34.9%) had a cervical length of 21-25 mm. Baseline characteristics were similar among all 4 groups. The shorter cervical length group was associated with a shorter time interval from enrollment to delivery (cervical length ≤10 mm, 10 weeks; cervical length 11-15 mm, 12.7 weeks; cervical length of 16-20 mm, 13 weeks; cervical length of 21-25 mm, 13.2 weeks; P = .006). Regardless of the cervical length measurement, delivery within 2 weeks was extremely uncommon (1 patient; 0.8%). The prevalence of spontaneous preterm birth at <32 weeks or <34 weeks was higher in women with a cervical length of ≤10 mm compared to those with a longer cervical length (P < .001).

CONCLUSIONS

The risk of spontaneous preterm birth in asymptomatic women with a sonographic short cervix increases as cervical length decreases. The risk is substantially higher in women with a cervical length of ≤10 mm. Women with a cervical length of ≤10 mm also had the shortest time interval to delivery. Nevertheless, delivery within 1 or 2 weeks is highly unlikely, regardless of the cervical length at the time of enrollment. Therefore, based on our data, we suggest that management decisions such as timing of administration of antenatal corticosteroids in asymptomatic patients with a cervical length of ≤25 mm at 23-28 weeks' gestation may be delayed until additional indications are present.

Recommended acceptable levels of maternal serum typical toxic metals from the perspective of spontaneous preterm birth in Shanxi Province, China

Preterm birth is an important issue of public reproductive health worldwide. The effects of the toxic metals on the likelihood of spontaneous preterm birth (SPB) are still under discussion. Our study aimed to investigate the association between maternal exposure to the five typical toxic metals or metalloid (i.e. arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), and lead (Pb)) and the SPB likelihood. The mothers delivering fetus with SPB (cases) and those with term healthy birth (controls) were chosen from a prospective birth cohort of 3201 women carried out in Shanxi Province, China. A total of 147 SPB cases and 381 controls were included in our nested case-control study. We collected maternal general information by questionnaire and collected their blood sample during recruitment. The serum concentrations of the five toxic metals were measured by inductively coupled-plasma mass spectrometry. We found that the demographic information between the cases and controls were well balanced. The participants in our study had relatively higher serum As concentration. For the other toxic metals (i.e. Cd, Cr, Hg, and Pb), their serum concentrations were overall in the middle range of those from general population. There were no significant associations of the serum concentrations of the five concerned toxic metals with the SPB likelihood. Our study results overall did not support that maternal exposure to As or Cd significantly contribute to the SPB risk in the current exposure level, as well as the other three toxic metals. We further proposed their upper concentration limits in maternal serum from the perspective of SPB likelihood during the early pregnant period, i.e. 18.2 ng/mL of As, 1.05 ng/mL of Cd, 0.96 ng/mL of Cr, 1.07 ng/mL of Hg, and 1.54 ng/mL of Pb.

Using Cervical Length Measurement for Lower Spontaneous Preterm Birth Rates Among Women With Threatened Preterm Labor

Spontaneous preterm birth is a leading cause of perinatal morbidity and mortality; however, accurate identification of women who will deliver prematurely after the onset of uterine contractions is still challenging, because less than 10% actually give birth within 7 days of presentation. Risk stratification in women with preterm contractions would allow targeting of interventions such as corticosteroids, magnesium sulfate, and maternal transfer to a perinatal center to those who will indeed deliver preterm. Moreover, unnecessary treatments associated with potential complications could be avoided in symptomatic women who are unlikely to deliver preterm. Fetal fibronectin testing and cervical length measurement are the most used methods to assess the risk of preterm birth among symptomatic women. Interventional studies in singleton gestations suggest that assessment of cervical length, unlike fetal fibronectin testing, improves diagnostic accuracy and leads to better perinatal outcomes.

POPPIE: protocol for a randomised controlled pilot trial of continuity of midwifery care for women at increased risk of preterm birth

Background

High rates of preterm births remain a UK public health concern. Preterm birth is a major determinant of adverse infant and longer-term outcomes, including survival, quality of life, psychosocial effects on the family and health care costs. We aim to test whether a model of care combining continuity of midwife care with rapid referral to a specialist obstetric clinic throughout pregnancy, intrapartum and the postpartum period is feasible and improves experience and outcomes for women at increased risk of preterm birth.

Methods

This pilot, hybrid, type 2 randomised controlled implementation trial will recruit 350 pregnant women at increased risk of preterm birth to a midwifery continuity of care intervention or standard care. The intervention will be provided from recruitment (antenatal), labour, birth and the postnatal period, in hospital and community settings and in collaboration with specialist obstetric clinic care, when required. Standard care will be the current maternity care provision by NHS midwives and obstetricians at the study site. Participants will be followed up until 6–8 weeks postpartum. The composite primary outcome is the appropriate initiation of any specified interventions related to the prevention and/or management of preterm labour and birth. Secondary outcomes are related to: recruitment and attrition rates; implementation; acceptability to women, health care professionals and stakeholders; health in pregnancy and other complications; intrapartum outcomes; maternal and neonatal postnatal outcomes; psycho-social health; quality of care; women’s experiences and health economic analysis. The trial has 80% power to detect a 15% increase in the rate of appropriate interventions (40 to 55%). The analysis will be by ‘intention to treat’ analysis.

Discussion

Little is known about the underlying reasons why and how models of midwifery continuity of care are associated with fewer preterm births, better maternal and infant outcomes and more positive experiences; nor how these models of care can be implemented successfully in the health services. This will be the first study to provide direct evidence regarding the effectiveness, implementation and evaluation of a midwifery continuity of care model and rapid access to specialist obstetric services for women at increased risk of preterm birth.

Trial registration

ISRCTN37733900. Retrospectively registered on 21 August 2017.

Threatened preterm birth: Validation of a nomogram to predict the individual risk of very preterm delivery in a secondary care center

INTRODUCTION

Very preterm delivery (22-32 weeks of gestation) remains a major cause of neonatal morbidity and mortality. The objective of this study was to validate a statistical model allowing to predict the risk of preterm delivery to use as a clinical decision-making tool for in utero transfer from a secondary to a tertiary care center.

METHODS

Retrospective observational study in a secondary care center (approximately 2500 births) in Paris, France. 137 women were admitted for threatened preterm delivery between 22 and 32 weeks. Women were retrospectively allocated to the following groups based on medical decision: "transfer group" (in utero transfer to a tertiary care unit) and "no transfer group" (no in utero transfer). The risk of preterm delivery within 48 h and before 32 weeks gestation was assessed for each group using a nomogram previously validated in a tertiary care center. The primary objective of the study was to determine the accuracy of the prediction model.

RESULTS

The discrimination and calibration of the nomogram were excellent (preterm delivery risk within 48 h, ROC AUC: 0.98, 95% CI: 0.95-1.00; probability of preterm delivery before 32 weeks gestation, ROC AUC: 0.94, 95% CI: 0.89-0.99). A threshold set at 0.16 helped minimize the risk of unnecessary in utero transfers with an excellent negative predictive value of 0.99.

CONCLUSIONS

We validated nomograms to predict the individual probability of preterm birth after admission in a secondary care center. Those nomograms could be helpful when making decisions regarding an in utero transfer to a tertiary care unit.

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

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

The 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.

Grading evidence from test accuracy studies: what makes it challenging compared with the grading of effectiveness studies?

Guideline panels need to process a sizeable amount of information to issue a decision on whether to recommend a health technology or not. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) is being frequently applied in guideline development to facilitate this task, typically for the synthesis of effectiveness research. Questions regarding the accuracy of medical tests are ubiquitous, and they temporally precede questions about therapy. However, literature summarising the experience of applying GRADE approach to accuracy evaluations is not as rich as one for effectiveness evidence. Type of study design (cross-sectional), two-dimensional nature of the performance measures (sensitivity and specificity), propensity towards a higher level of between-study heterogeneity, poor reporting of quality features and uncertainty about how best to assess for publication bias among other features make this task challenging. This article presents solutions adopted to addresses above challenges for judicious estimation of the strength of test accuracy evidence used to inform evidence syntheses for guideline development.

Predictors of preterm birth

Cervical length (CL) measured by transvaginal ultrasound examination (TVUE) best identifies the risk for preterm birth (PTB). It identifies women at risk who can benefit from corticosteroids or in utero transfer. Early screening improves effectiveness of tocolysis. It reduces iatrogenicity and cost. In preterm premature rupture of membranes (PPROM), CL is devoid of infectious risk and predicts duration of the latency phase but not the risk of perinatal sepsis. Asymptomatic women at risk should be screened at a 2-week interval starting from 16 to 18 weeks, up to 24 weeks. CLs <10th centile are at risk of PTB, especially with decrease in CL after 16 weeks. Repeat ultrasound improves predictive values. Stable CL calls for term delivery. Funneling does not improve predictivity of CL. In twin pregnancies, CL reduces unnecessary interventions. In symptomatic women, fetal fibronectin performs less than CL. Its combination with inconclusive CL has not emerged productive through randomized controlled trials (RCTs), and studies with homogeneous management for preterm labor (PTL) suggest that up to 15% of unjustified hospitalizations and treatment could be avoided.

Vaginal progesterone is as effective as cervical cerclage to prevent preterm birth in women with a singleton gestation, previous spontaneous preterm birth, and a short cervix: updated indirect comparison meta-analysis

BACKGROUND

An indirect comparison meta-analysis published in 2013 reported that both vaginal progesterone and cerclage are equally efficacious for preventing preterm birth and adverse perinatal outcomes in women with a singleton gestation, previous spontaneous preterm birth, and a sonographic short cervix. The efficacy of vaginal progesterone has been challenged after publication of the OPPTIMUM study. However, this has been resolved by an individual patient-data meta-analysis (Am J Obstet Gynecol. 2018;218:161-180).

OBJECTIVE

To compare the efficacy of vaginal progesterone and cerclage in preventing preterm birth and adverse perinatal outcomes in women with a singleton gestation, previous spontaneous preterm birth, and a midtrimester sonographic short cervix.

DATA SOURCES

MEDLINE, EMBASE, LILACS, and CINAHL (from their inception to March 2018); Cochrane databases, bibliographies, and conference proceedings.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials comparing vaginal progesterone to placebo/no treatment or cerclage to no cerclage in women with a singleton gestation, previous spontaneous preterm birth, and a sonographic cervical length <25 mm.

STUDY APPRAISAL AND SYNTHESIS METHODS

Updated systematic review and adjusted indirect comparison meta-analysis of vaginal progesterone vs cerclage using placebo/no cerclage as the common comparator. The primary outcomes were preterm birth <35 weeks of gestation and perinatal mortality. Pooled relative risks (RRs) with 95% confidence intervals were calculated.

RESULTS

Five trials comparing vaginal progesterone vs placebo (265 women) and 5 comparing cerclage vs no cerclage (504 women) were included. Vaginal progesterone, compared to placebo, significantly reduced the risk of preterm birth <35 and <32 weeks of gestation, composite perinatal morbidity/mortality, neonatal sepsis, composite neonatal morbidity, and admission to the neonatal intensive care unit (RRs from 0.29 to 0.68). Cerclage, compared to no cerclage, significantly decreased the risk of preterm birth <37, <35, <32, and <28 weeks of gestation, composite perinatal morbidity/mortality, and birthweight <1500 g (RRs from 0.64 to 0.70). Adjusted indirect comparison meta-analyses did not show statistically significant differences between vaginal progesterone and cerclage in the reduction of preterm birth or adverse perinatal outcomes.

CONCLUSION

Vaginal progesterone and cerclage are equally effective for preventing preterm birth and improving perinatal outcomes in women with a singleton gestation, previous spontaneous preterm birth, and a midtrimester sonographic short cervix. The choice of treatment will depend on adverse events and cost-effectiveness of interventions and patient/physician's preferences.

Cost-effectiveness of diagnostic tests for threatened preterm labor in singleton pregnancy in France

BACKGROUND

Previous studies have showed that the early diagnosis of threatened preterm labor decreases neonatal morbidity and mortality, avoids maternal morbidity induced by antepartum bed rest and unnecessary treatment, and reduces costs. Although there are many diagnostic tests, none is clearly recommended by international guidelines. The aim of our study was to compare seven diagnostic methods in terms of effectiveness and cost using a decision analysis model in singleton pregnancy presenting threatened preterm labor, between 24 and 34 weeks of gestation.

METHODS

Seven diagnostic strategies based on individual or combined use of the following tests: cervical length, cervical fibronectin test, cervical interleukin test and protein in maternal serum, were compared using a decision analysis model. Effectiveness was expressed in terms of serious adverse neonatal events avoided (neonatal morbidity and mortality) at the hospital discharge. The economic analysis was performed from the health care system perspective. Deterministic and probabilistic analyses were performed to test the robustness of the model.

RESULTS

At 24-34 weeks of gestation, the association of cervical length and qualitative fibronectin was the most efficient strategy dominating all alternatives, reducing the perinatal death or severe neonatal morbidity rate up to 15% and the costs up to 31% according to the gestational age. This result was confirmed by the deterministic sensitivity analyses. The probabilistic analysis showed that the association of cervical length and qualitative fibronectin dominated cervical length < 15 mm in more than 90% of the simulations. The comparison with the other tests revealed more uncertainty.

CONCLUSIONS

A test using cervical length and qualitative fetal fibronectin appears to be the best diagnostic strategy. Decisions regarding its generalization and funding in France in this population of women should take into account the high, lifetime costs induced by prematurity.

Study protocol: quantitative fibronectin to help decision-making in women with symptoms of preterm labour (QUIDS) part 2, UK Prospective Cohort Study

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 (fFN) concentration, in combination with clinical risk factors.

METHODS AND ANALYSIS

The study will evaluate the Rapid fFN 10Q System (Hologic, Marlborough, Massachusetts, USA) which quantifies fFN in a vaginal swab. In QUIDS part 2, we will perform a prospective cohort study in at least eight UK consultant-led maternity units, in women with symptoms of preterm labour at 22⁺⁰ to 34⁺⁶ weeks gestation to externally validate a prognostic model developed in QUIDS part 1. The effects of quantitative fFN on anxiety will be assessed, and acceptability of the test and prognostic model will be evaluated in a subgroup of women and clinicians (n=30). The sample size is 1600 women (with estimated 96-192 events of preterm delivery within 7 days of testing). Clinicians will be informed of the qualitative fFN result (positive/negative) but be blinded to quantitative fFN result. Research midwives will collect outcome data from the maternal and neonatal clinical records. The final validated prognostic model will be presented as a mobile or web-based application.

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).

VERSION

Protocol V.2, Date 1 November 2016.

TRIAL REGISTRATION NUMBER

ISRCTN 41598423andCPMS: 31277.

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.

Electrohysterography in the diagnosis of preterm birth: a review

Preterm birth (PTB) is one of the most common and serious complications in pregnancy. About 15 million preterm neonates are born every year, with ratios of 10-15% of total births. In industrialized countries, preterm delivery is responsible for 70% of mortality and 75% of morbidity in the neonatal period. Diagnostic means for its timely risk assessment are lacking and the underlying physiological mechanisms are unclear. Surface recording of the uterine myoelectrical activity (electrohysterogram, EHG) has emerged as a better uterine dynamics monitoring technique than traditional surface pressure recordings and provides information on the condition of uterine muscle in different obstetrical scenarios with emphasis on predicting preterm deliveries.

OBJECTIVE

A comprehensive review of the literature was performed on studies related to the use of the electrohysterogram in the PTB context.

APPROACH

This review presents and discusses the results according to the different types of parameter (temporal and spectral, non-linear and bivariate) used for EHG characterization.

MAIN RESULTS

Electrohysterogram analysis reveals that the uterine electrophysiological changes that precede spontaneous preterm labor are associated with contractions of more intensity, higher frequency content, faster and more organized propagated activity and stronger coupling of different uterine areas. Temporal, spectral, non-linear and bivariate EHG analyses therefore provide useful and complementary information. Classificatory techniques of different types and varying complexity have been developed to diagnose PTB. The information derived from these different types of EHG parameters, either individually or in combination, is able to provide more accurate predictions of PTB than current clinical methods. However, in order to extend EHG to clinical applications, the recording set-up should be simplified, be less intrusive and more robust-and signal analysis should be automated without requiring much supervision and yield physiologically interpretable results.

SIGNIFICANCE

This review provides a general background to PTB and describes how EHG can be used to better understand its underlying physiological mechanisms and improve its prediction. The findings will help future research workers to decide the most appropriate EHG features to be used in their analyses and facilitate future clinical EHG applications in order to improve PTB prediction.

Vaginal progesterone for preventing preterm birth and adverse perinatal outcomes in singleton gestations with a short cervix: a meta-analysis of individual patient data

BACKGROUND

The efficacy of vaginal progesterone for preventing preterm birth and adverse perinatal outcomes in singleton gestations with a short cervix has been questioned after publication of the OPPTIMUM study.

OBJECTIVE

To determine whether vaginal progesterone prevents preterm birth and improves perinatal outcomes in asymptomatic women with a singleton gestation and a midtrimester sonographic short cervix.

STUDY DESIGN

We searched MEDLINE, EMBASE, LILACS, and CINAHL (from their inception to September 2017); Cochrane databases; bibliographies; and conference proceedings for randomized controlled trials comparing vaginal progesterone vs placebo/no treatment in women with a singleton gestation and a midtrimester sonographic cervical length ≤25 mm. This was a systematic review and meta-analysis of individual patient data. The primary outcome was preterm birth <33 weeks of gestation. Secondary outcomes included adverse perinatal outcomes and neurodevelopmental and health outcomes at 2 years of age. Individual patient data were analyzed using a 2-stage approach. Pooled relative risks with 95% confidence intervals were calculated. Quality of evidence was assessed using the GRADE methodology.

RESULTS

Data were available from 974 women (498 allocated to vaginal progesterone, 476 allocated to placebo) with a cervical length ≤25 mm participating in 5 high-quality trials. Vaginal progesterone was associated with a significant reduction in the risk of preterm birth <33 weeks of gestation (relative risk, 0.62; 95% confidence interval, 0.47-0.81; P = .0006; high-quality evidence). Moreover, vaginal progesterone significantly decreased the risk of preterm birth <36, <35, <34, <32, <30, and <28 weeks of gestation; spontaneous preterm birth <33 and <34 weeks of gestation; respiratory distress syndrome; composite neonatal morbidity and mortality; birthweight <1500 and <2500 g; and admission to the neonatal intensive care unit (relative risks from 0.47-0.82; high-quality evidence for all). There were 7 (1.4%) neonatal deaths in the vaginal progesterone group and 15 (3.2%) in the placebo group (relative risk, 0.44; 95% confidence interval, 0.18-1.07; P = .07; low-quality evidence). Maternal adverse events, congenital anomalies, and adverse neurodevelopmental and health outcomes at 2 years of age did not differ between groups.

CONCLUSION

Vaginal progesterone decreases the risk of preterm birth and improves perinatal outcomes in singleton gestations with a midtrimester sonographic short cervix, without any demonstrable deleterious effects on childhood neurodevelopment.

First-trimester vaginal microbiome diversity: A potential indicator of preterm delivery risk

Preterm birth is a leading cause of global neonate mortality. Hospitalization costs associated with preterm deliveries present a huge economic burden. Existing physical/biochemical markers for predicting preterm birth risk are mostly suited for application at mid/late pregnancy stages, thereby leaving very short time (between diagnosis and delivery) for adopting appropriate intervention strategies. Recent studies indicating correlations between pre/full-term delivery and the composition of vaginal microbiota in pregnant women have opened new diagnostic possibilities. In this study, we performed a thorough meta-analysis of vaginal microbiome datasets to evaluate the utility of popular diversity and inequality measures for predicting, at an early stage, the risk of preterm delivery. Results indicate significant differences (in diversity measures) between ‘first-trimester’ vaginal microbiomes obtained from women with term and preterm outcomes, indicating the potential diagnostic utility of these measures. In this context, we introduce a novel diversity metric that has significantly better diagnostic ability as compared to established diversity measures. The metric enables ‘early’ and highly accurate prediction of preterm delivery outcomes, and can potentially be deployed in clinical settings for preterm birth risk-assessment. Our findings have potentially far reaching implications in the fight against neonatal deaths due to preterm birth.

Detection and risk stratification of women at high risk of preterm birth in rural communities near Nagpur, India

BACKGROUND

Presently, preterm birth is globally the leading cause of neonatal mortality. Prompt community based identification of women at high risk for preterm births (HRPB) can either help to avert preterm births or avail effective interventions to reduce neonatal mortality due to preterm births. We evaluated the performance of a package to train community workers to detect the presence of signs or symptoms of HRPB.

METHODS

Pregnant women enrolled in the intervention arm of a cluster randomized trial of Antenatal Corticosteroids (ACT Trial) conducted at Nagpur, India were informed about 4 directly observable signs and symptoms of preterm labor. Community health workers actively monitored these women from 24 to 36 weeks of gestation for these signs or symptoms. If they were present (HRPB positive) the identified women were brought to government health facilities for assessment and management. HRPB positive could also be determined by the provider if the woman presented directly to the facility. Risk stratification was based on the number of signs or symptoms present. The outcome of preterm birth was based on the clinical assessment of gestational age < 37 weeks at delivery or a birth weight of <2000 g.

RESULTS

Between July 1, 2012 and 30 November, 2013, 686 of 7050 (9.7%) pregnant women studied, delivered preterm. 732 (10.4%) women were HRPB positive, of whom 333 (45.5%) delivered preterm. Of the remaining 6318(89.6%) HRPB negative women 353 (5.6%) delivered preterm. The likelihood ratio (LR) of a preterm birth in the HRPB positives was 8.14 (95% confidence interval 7.16-9.26). The LR of a preterm birth increased in women who had more signs or symptoms of HRBP (p < 0.00001). More signs or symptoms of HRPB were also associated with a shorter time to delivery, lower birth weight and higher rates of stillbirths, neonatal deaths and postnatal complications. Addition of risk stratification improved the prediction of preterm delivery (Integrated Discrimination Improvement 17% (95% CI 15-19%)).

CONCLUSIONS

The package for detection of signs and symptoms of HRPB is feasible, promising and likely to improve management of preterm labor.

TRIAL REGISTRATION

NCT01073475 on February 21, 2010 and NCT01084096 on March 9, 2010.

Performance of cervical phIGFBP-1 test alone or combined with short cervical length to predict spontaneous preterm birth in symptomatic women

We aimed to assess the accuracy of cervical phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) test alone or in combination with cervical length (CL), to predict preterm birth (PTB) in symptomatic women. We performed a prospective cohort study from 2012 to 2015 including singleton pregnancies with symptoms of preterm labor, intact membranes and CL < 25 mm at 24-34 weeks 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 180 women, 21 (11.7%) had a positive phIGFBP-1 test. Spontaneous PTB occurred within 7 days, 14 days of testing and before 34 weeks and 37 weeks in 7.8%, 10.6%, 12.9% and 28.8%, respectively. The phIGFBP-1 test had a low predictive performance for all studied outcomes varying for positive likelihood ratios (2.8 to 3.4) and negative likelihood ratios (0.8). Combining phIGFBP-1 and CL did not increase its predictive ability. After adjustment, positive phIGFBP-1 test was no more independently associated with a delivery within 7 days (p = 0.55), unlike CL < 15 mm (p = 0.04). In conclusion, phIGFBP-1 test alone or in combination with CL has a low predictive accuracy to predict PTB in symptomatic women.

Can stress biomarkers predict preterm birth in women with threatened preterm labor?

BACKGROUND

Preterm birth is a major paediatric challenge difficult to prevent and with major adverse outcomes. Prenatal stress plays an important role on preterm birth; however, there are few stress-related models to predict preterm birth in women with Threatened Preterm Labor (TPL).

OBJECTIVE

The aim of this work is to study the influence of stress biomarkers on time until birth in TPL women.

METHODS

Eligible participants were pregnant women between 24 and 31 gestational weeks admitted to the hospital with TPL diagnosis (n=166). Stress-related biomarkers (α-amylase and cortisol) were determined in saliva samples after TPL diagnosis. Participants were followed-up until labor. A parametric survival model was constructed based on α-amylase, cortisol), TPL gestational week, age, parity, and multiple pregnancy. The model was adjusted using a logistic distribution and it was implemented as a nomogram to predict the labor probability at 7- and 14-day term.

RESULTS

The time until labor was associated with cortisol (p=0.001), gestational week at TPL diagnosis (p=0.004), and age (p=0.02). Importantly, high cortisol levels at TPL diagnosis were predictive of latency to labor. Validation of the model yielded an optimum corrected AUC value of 0.63.

CONCLUSIONS

High cortisol levels at TPL diagnosis may have an important role in the preterm birth prediction. Our statistical model implemented as a nomogram provided accurate predictions of individual prognosis of pregnant women.

Timing of delivery in a high-risk obstetric population: a clinical prediction model

BACKGROUND

The efficacy of antenatal corticosteroid treatment for women with threatened preterm birth depends on timely administration within 7 days before delivery. We modelled the probability of delivery within 7 days of admission to hospital among women presenting with threatened preterm birth, using routinely collected clinical characteristics.

METHODS

Data from the Canadian Perinatal Network (CPN) were used, 2005-11, including women admitted to hospital with preterm labour, preterm pre-labour rupture of membranes, short cervix without contractions, or dilated cervix or prolapsed membranes without contractions at preterm gestation. Women with fetal anomaly, intrauterine fetal demise, twin-to-twin transfusion syndrome, and quadruplets were excluded. Logistic regression was undertaken to create a predictive model that was assessed for its calibration capacity, stratification ability, and classification accuracy (ROC curve).

RESULTS

We included 3012 women admitted at 24-28 weeks gestation, or readmitted at up to 34 weeks gestation, to 16 tertiary-care CPN hospitals. Of these, 1473 (48.9%) delivered within 7 days of admission. Significant predictors of early delivery included maternal age, parity, gestational age at admission, smoking, preterm labour, prolapsed membranes, preterm pre-labour rupture of membranes, and antepartum haemorrhage. The area under the ROC curve was 0.724 (95% CI 0.706-0.742).

CONCLUSION

We propose a useful tool to improve prediction of delivery within 7 days after admission among women with threatened preterm birth. This information is important for optimal corticosteroid treatment.

Estimation of preterm labor immediacy by nonlinear methods

Preterm delivery affects about one tenth of human births and is associated with an increased perinatal morbimortality as well as with remarkable costs. Even if there are a number of predictors and markers of preterm delivery, none of them has a high accuracy. In order to find quantitative indicators of the immediacy of labor, 142 cardiotocographies (CTG) recorded from women consulting because of suspected threatened premature delivery with gestational ages comprehended between 24 and 35 weeks were collected and analyzed. These 142 samples were divided into two groups: the delayed labor group (n = 75), formed by the women who delivered more than seven days after the tocography was performed, and the anticipated labor group (n = 67), which corresponded to the women whose labor took place during the seven days following the recording. As a means of finding significant differences between the two groups, some key informational properties were analyzed by applying nonlinear techniques on the tocography recordings. Both the regularity and the persistence levels of the delayed labor group, which were measured by Approximate Entropy (ApEn) and Generalized Hurst Exponent (GHE) respectively, were found to be significantly different from the anticipated labor group. As delivery approached, the values of ApEn tended to increase while the values of GHE tended to decrease, suggesting that these two methods are sensitive to labor immediacy. On this paper, for the first time, we have been able to estimate childbirth immediacy by applying nonlinear methods on tocographies. We propose the use of the techniques herein described as new quantitative diagnosis tools for premature birth that significantly improve the current protocols for preterm labor prediction worldwide.

Effectiveness of the contemporary treatment of preterm labor: a comparison with a historical cohort

OBJECTIVE

To compare the effectiveness of contemporary treatment of preterm labor to a historical cohort.

STUDY DESIGN

Retrospective matched case-control study to compare the outcomes of patients that were treated for preterm labor at the University Hospital of Tuebingen, Germany in 2014/2015 (current treatment cohort) and 2006/2007 (historical cohort). The study included women with singleton gestations who were admitted with the diagnosis of preterm labor between 24 + 0 and 34 + 0 weeks' gestation and a cervical length of ≤15 mm. Women in the historical cohort were hospitalized until either 34 weeks' gestation or until complete cessation of uterine contractions. They were treated with intravenous beta-mimetics continuously, received antibiotics based on the vaginal culture and corticosteroids regardless of cervical length measurement. Bed rest was always recommended. The current treatment cohort was tocolyzed with an oral calcium channel blocker for approximately 3 days followed by vaginal progesterone until 34 weeks' gestation. Corticosteroids were given only if the cervical length is ≤15 mm. Bed rest was not recommended.

RESULTS

The study population consisted of 110 pregnancies, 55 in the historical cohort and 55 in the current treatment cohort. At the time of admission, mean gestational age in both groups was 29.3 and 29.7 weeks. In the historical and current treatment cohort the length of the hospitalization was 24.0 and 5.5 days and tocolysis was given for 19.5 and 3.4 days, respectively. In the historical cohort, mean gestational age at delivery was 35.6 weeks. In 63.6% cases delivery occurred prior to 37 weeks. In the current treatment group mean gestational age at the delivery was 37.0 weeks and 36.4% were delivered prior to 37 weeks.

CONCLUSION

Short-term hospitalization and tocolysis followed by vaginal progesterone for maintenance tocolysis is more effective than a protocol which includes long-term hospital stay, beta-mimetics, antibiotics, and bed rest.

Applying Precision Public Health to Prevent Preterm Birth

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

Vaginal progesterone decreases preterm birth and neonatal morbidity and mortality in women with a twin gestation and a short cervix: an updated meta-analysis of individual patient data

OBJECTIVE

To assess the efficacy of vaginal progesterone for the prevention of preterm birth and neonatal morbidity and mortality in asymptomatic women with a twin gestation and a sonographic short cervix (cervical length ≤ 25 mm) in the mid-trimester.

METHODS

This was an updated systematic review and meta-analysis of individual patient data (IPD) from randomized controlled trials comparing vaginal progesterone with placebo/no treatment in women with a twin gestation and a mid-trimester sonographic cervical length ≤ 25 mm. MEDLINE, EMBASE, POPLINE, CINAHL and LILACS (all from inception to 31 December 2016), the Cochrane Central Register of Controlled Trials, Research Registers of ongoing trials, Google Scholar, conference proceedings and reference lists of identified studies were searched. The primary outcome measure was preterm birth < 33 weeks' gestation. Two reviewers independently selected studies, assessed the risk of bias and extracted the data. Pooled relative risks (RRs) with 95% confidence intervals (CI) were calculated.

RESULTS

IPD were available for 303 women (159 assigned to vaginal progesterone and 144 assigned to placebo/no treatment) and their 606 fetuses/infants from six randomized controlled trials. One study, which included women with a cervical length between 20 and 25 mm, provided 74% of the total sample size of the IPD meta-analysis. Vaginal progesterone, compared with placebo/no treatment, was associated with a statistically significant reduction in the risk of preterm birth < 33 weeks' gestation (31.4% vs 43.1%; RR, 0.69 (95% CI, 0.51-0.93); moderate-quality evidence). Moreover, vaginal progesterone administration was associated with a significant decrease in the risk of preterm birth < 35, < 34, < 32 and < 30 weeks' gestation (RRs ranging from 0.47 to 0.83), neonatal death (RR, 0.53 (95% CI, 0.35-0.81)), respiratory distress syndrome (RR, 0.70 (95% CI, 0.56-0.89)), composite neonatal morbidity and mortality (RR, 0.61 (95% CI, 0.34-0.98)), use of mechanical ventilation (RR, 0.54 (95% CI, 0.36-0.81)) and birth weight < 1500 g (RR, 0.53 (95% CI, 0.35-0.80)) (all moderate-quality evidence). There were no significant differences in neurodevelopmental outcomes at 4-5 years of age between the vaginal progesterone and placebo groups.

CONCLUSION

Administration of vaginal progesterone to asymptomatic women with a twin gestation and a sonographic short cervix in the mid-trimester reduces the risk of preterm birth occurring at < 30 to < 35 gestational weeks, neonatal mortality and some measures of neonatal morbidity, without any demonstrable deleterious effects on childhood neurodevelopment. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.