Patients with an ultrasonographic cervical length < or =15 mm have nearly a 50% risk of early spontaneous preterm delivery

Vaginal Progesterone to Prevent Spontaneous Preterm Birth in Women With a Sonographic Short Cervix: The Story of the PREGNANT Trial

The PREGNANT trial was a randomized, placebo-controlled, multicenter trial designed to determine the efficacy and safety of vaginal progesterone (VP) to reduce the risk of birth < 33 weeks and of neonatal complications in women with a sonographic short cervix (10 to 20 mm) in the mid-trimester (19 to 23 6/7 wk). Patients allocated to receive VP had a 45% lower rate of preterm birth (8.9% vs 16.1%; relative risk = 0.55; 95% CI: 0.33-0.92). Neonates born to mothers allocated to VP had a 60% reduction in the rate of respiratory distress syndrome. This article reviews the background, design, execution, interpretation, and impact of the PREGNANT Trial.

Early Magnetic Resonance Imaging Measurements and Prediction of Second Trimester Pregnancy Loss: a Nomogram Model Analysis

Objective

To investigate the magnetic resonance imaging (MRI) features of women with prior second-trimester pregnancy loss, and to establish a nomogram prediction model for subsequent miscarriage.

Methods

A retrospective cohort study of women with prior second-trimester pregnancy loss from January 2018 to December 2021 in Second Affiliated Hospital of Soochow University was performed. A total of 245 patients were included. Data from January 2018 to December 2019 were used to construct the model, and data from January 2020 to December 2021 were used to evaluate the model. Data on maternal demographic characteristics, MRI cervical measurements were extracted. The prediction model was constructed with independent variables determined by multivariate logistic regression analyses. Through receiver-operating characteristic (ROC) curve analysis, the predictive ability of the model for subsequent second trimester pregnancy loss in women was evaluated, and internal validation was performed through validation data.

Results

Thin cervix was observed in 77 (31.42%) women with prior second-trimester pregnancy loss, the mean longitudinal diameter of cervical canal on MRI was 11.76±2.75mm. The model reached a sensitivity of 80%, specificity of 75.90%, positive predictive value (PPV) of 55.80% and negative predictive value of 90.90%; ROC characteristics proved that the model was superior to any single parameter with an AUC of 0.826.

Conclusion

Our observations showed that thin cervix and longitudinal diameter of cervical canal reliably predicted second trimester pregnancy loss. We developed and validated a nomogram model to predict the individual probability of second trimester pregnancy loss in the next pregnancy and hopefully improve the prediction and indication of interventions.

Differences in cervical length during the second trimester among normal weight, overweight and obese women: A systematic review and meta-analysis

Objective

Maternal obesity has been previously linked to increased risk of preterm birth; however, the actual pathophysiology behind this observation remains unknown. Cervical length seems to differentiate among overweight, obese and extremely obese patients, compared to normal weight women. However, to date the actual association between body mass index and cervical length remains unknown. In this systematic review, accumulated evidence is presented to help establish clinical implementations and research perspectives.

Methods

We searched Medline, Scopus, the Cochrane Central Register of Controlled Trials CENTRAL, Google Scholar, and Clinicaltrials.gov databases from inception till February 2023. Observational studies that reported on women undergone ultrasound assessment of their cervical length during pregnancy were included, when there was data regarding their body mass index. Statistical meta-analysis was performed with RStudio. The quality of the included studies was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS).

Results

Overall, 20 studies were included in this systematic review and 12 in the meta-analysis. Compared to women with normal weight, underweight women were not associated with increased risk of CL < 15 mm or < 30 mm and their mean CL was comparable (MD -1.51; 95% CI -3.07, 0.05). Overweight women were found to have greater cervical length compared to women with normal weight (MD 1.87; 95% CI 0.52, 3.23) and had a lower risk of CL < 30 mm (OR 0.65; 95% CI 0.47, 0.90).

Conclusion

Further research into whether BMI is associated with cervical length in pregnant women is deemed necessary, with large, well-designed, prospective cohort studies with matched control group.

Bioengineering and the cervix: The past, current, and future for addressing preterm birth

The uterine cervix plays two important but opposing roles during pregnancy - as a mechanical barrier that maintains the fetus for nine months and as a compliant structure that dilates to allow for the delivery of a baby. In some pregnancies, however, the cervix softens and dilates prematurely, leading to preterm birth. Bioengineers have addressed and continue to address the lack of reduction in preterm birth rates by developing novel technologies to diagnose, prevent, and understand premature cervical remodeling. This article highlights these existing and emerging technologies and concludes with open areas of research related to the cervix and preterm birth that bioengineers are currently well-positioned to address.

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.

[Pelvic exam in gynecology and obstetrics: Guidelines for clinical practice]

OBJECTIVE

To provide guidelines for the pelvic clinical exam in gynecology and obstetrics.

MATERIAL AND METHODS

A multidisciplinary experts consensus committee of 45 experts was formed, including representatives of patients' associations and users of the health system. The entire guidelines process was conducted independently of any funding. The authors were advised to follow the rules of the Grading of Recommendations Assessment, Development and Evaluation (GRADE®) system to guide assessment of quality of evidence. The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized.

METHODS

The committee studied 40 questions within 4 fields for symptomatic or asymptomatic women (emergency conditions, gynecological consultation, gynecological diseases, obstetrics, and pregnancy). Each question was formulated in a PICO (Patients, Intervention, Comparison, Outcome) format and the evidence profiles were produced. The literature review and recommendations were made according to the GRADE® methodology.

RESULTS

The experts' synthesis work and the application of the GRADE method resulted in 27 recommendations. Among the formalized recommendations, 17 present a strong agreement, 7 a weak agreement and 3 an expert consensus agreement. Thirteen questions resulted in an absence of recommendation due to lack of evidence in the literature.

CONCLUSIONS

The need to perform clinical examination in gynecological and obstetrics patients was specified in 27 pre-defined situations based on scientific evidence. More research is required to investigate the benefit in other cases.

Analysis of pregnancy outcomes in patients undergoing ultrasound-indicated cerclage and identification the influence factors for predicting preterm birth: A retrospective study of 87 cases

OBJECTIVE

To investigate the factors influencing preterm birth in patients after ultrasound-indicated cerclage with different cervical lengths (CL), and explore the optimal cut-off value of CL.

MATERIALS AND METHODS

The retrospective study included 87 pregnant women with a history of preterm birth and second-trimester loss that received ultrasound-indicated cerclage in our hospital between January 2004 and April 2021. Groups were divided by CL at the demarcation point of 1.0, 1.5 and 2.0 cm respectively. The pregnancy outcomes were compared. Logistic regression analysis was performed to assess the independent influence factors. Receiver-operating characteristic (ROC) curves were constructed and the area under the curve (AUC) was used to compare the prediction capability of the associated factors.

RESULTS

Significant difference was found in terms of patients delivered at ≥32 weeks of gestation (19 [55.9%]vs. 41 [77.4%], p < 0.05) and neonatal birth weight (2495 [1138,3185]vs. 2995 [2155,3235] g, p < 0.05), when the CL was categorized at the demarcation point of 1.5 cm. Body mass index (BMI) (odds ratio [OR] = 1.224, p < 0.05), a history of preterm birth and second-trimester loss (OR = 3.153, p < 0.05), and C-reactive protein (CRP) > 5 mg/L (OR = 8.097, p < 0.05) were independent risk factors for gestational age more than 28 weeks. The AUC of joint predictor A included those factors was 0.849 (95% CI: 0.701-0.998, p < 0.05). CRP>5 mg/L was found to be a significant independent risk factor for different gestational age at delivery.

CONCLUSIONS

A CL of 1.5 cm was the optimal cut-off value that could help women who underwent serial CL surveillance choose ultrasound-indicated cerclage at an appropriate time. High BMI, more history of preterm birth and second-trimester loss and abnormal CRP could be used as combined predictors to recognize the risk of preterm birth (<28 weeks) post-surgery.

Effect of preoperative low-normal cervical length on perinatal outcome after laparotomy-assisted fetoscopic spina bifida repair

OBJECTIVE

To determine if preoperative cervical length in the low-normal range increases the risk of adverse perinatal outcome in patients undergoing fetoscopic spina bifida repair.

METHODS

This was a retrospective cohort study of patients who underwent fetal spina bifida repair between September 2014 and May 2022 at a single center. Cervical length was measured on transvaginal ultrasound during the week before surgery. Eligibility for laparotomy-assisted fetoscopic spina bifida repair was as per the criteria of the Management of Myelomeningocele Study, although maternal body mass index (BMI) up to 40 kg/m² was allowed. Laparotomy-assisted fetoscopic spina bifida repair was performed, with carbon dioxide insufflation via two 12-French ports in the exteriorized uterus. All patients received the same peri- and postoperative tocolysis regimen, including magnesium sulfate, nifedipine and indomethacin. Postoperative follow-up ultrasound scans were performed either weekly (< 32 weeks' gestation) or twice a week (≥ 32 weeks). Perinatal outcome was compared between patients with a preoperative cervical length of 25-30 mm vs those with a cervical length > 30 mm. Logistic regression analyses and generalized linear mixed regression analyses were used to predict delivery at less than 30, 34 and 37 weeks' gestation.

RESULTS

The study included 99 patients with a preoperative cervical length > 30 mm and 12 patients with a cervix 25-30 mm in length. One further case which underwent spina bifida repair was excluded because cervical length was measured > 1 week before surgery. No differences in maternal demographics, gestational age (GA) at surgery, duration of surgery or duration of carbon dioxide uterine insufflation were observed between groups. Cases with low-normal cervical length had an earlier GA at delivery (median (range), 35.2 (25.1-39.7) weeks vs 38.2 (26.0-40.9) weeks; P = 0.01), higher rates of delivery at < 34 weeks (41.7% vs 10.2%; P = 0.01) and < 30 weeks (25.0% vs 1.0%; P < 0.01) and a higher rate of preterm prelabor rupture of membranes (PPROM) (58.3% vs 26.3%; P = 0.04) at an earlier GA (mean ± SD, 29.3 ± 4.0 weeks vs 33.0 ± 2.4 weeks; P = 0.05) compared to those with a normal cervical length. Neonates of cases with low-normal cervical length had a longer stay in the neonatal intensive care unit (20 (7-162) days vs 9 (3-253) days; P = 0.02) and higher rates of respiratory distress syndrome (50.0% vs 14.4%; P < 0.01), sepsis (16.7% vs 1.0%; P = 0.03), necrotizing enterocolitis (16.7% vs 0%; P = 0.01) and retinopathy (33.3% vs 1.0%; P < 0.01). There was an association between preoperative cervical length and risk of delivery at < 30 weeks which was significant only for patients with a maternal BMI < 25 kg/m² (odds ratio, 0.37 (95% CI, 0.07-0.81); P = 0.02).

CONCLUSIONS

Low-normal cervical length (25-30 mm) as measured before in-utero laparotomy-assisted fetoscopic spina bifida repair may increase the risk of adverse perinatal outcomes, including PPROM and preterm birth, leading to higher rates of neonatal complications. These data warrant further research and are of critical relevance for clinical teams considering the eligibility of patients for in-utero spina bifida repair. Based on this evidence, patients with a low-normal cervical length should be aware of their increased risk for adverse perinatal outcome. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A novel method for assessing the condition of the cervix before labor induction: Cervical length/thickness ratio

Background/Aim: Due to the increasing cesarean rates globally, new methods for supporting vaginal delivery and induction of successful vaginal delivery are still being developed. We aimed to obtain an easy-to-use method that can predict the effectiveness of cervical ripening agents before labor induction. So, we presented the effects on labor by measuring the thickness of the cervix and the cervical length/thickness ratio ultrasonographically. Methods: In this prospective cohort study, we evaluated 183 pregnant between 37 and 41 weeks of gestational age and will apply vaginal delivery induction. Before oxytocin induction, we applied 10 mg dinoprostone vaginally to women whose cervix was stiff. We started labor induction with oxytocin when regular uterine contractions or dilatation occurred. We used the Bishop Scoring System for favorable cervix defining. Then, we compared the groups with successful and unsuccessful cervical ripening regarding cervical length and thickness parameters. Results: The mean cervical thickness of the pregnant women with successful cervical ripening was 34.5 (7.5) mm before treatment, while the mean values of the unsuccessful group were 29.2 (9.1) mm (P < 0.001). The cervical length did not differ between the two groups (31.6 [8.2] vs. 32.5 [6.8], P = 0.44), while the cervical length/thickness ratio was lower in the group with successful ripening (0.9 [0.38–2], P < 0.001). Cervical length/thickness ratio was the highest predictor of the favorable cervix with dinoprostone. Each 1 unit decrease in the length/thickness ratio of the cervix increases the preparation of the cervix for induction by 0.25 times (P = 0.04). A successful response to dinoprostone can be obtained if the cervical length/thickness ratio is <1.06 mm (P < 0.001). Conclusion: In conclusion, assessing the cervix’s condition before labor induction by measuring the cervical length/thickness ratio may be a good predictor of cervical ripening activity.

Development of a New Biomarker Model for Predicting Preterm Birth in Cervicovaginal Fluid

Preterm birth (PTB) is a social problem that adversely affects not only the survival rate of the fetus, but also the premature babies and families, so there is an urgent need to find accurate biomarkers. We noted that among causes, eubiosis of the vaginal microbial community to dysbiosis leads to changes in metabolite composition. In this study, short chain fatty acids (SCFAs) representing dysbiosis were derivatized using (N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide, MTBSTFA) and targeted analysis was conducted in extracted organic phases of cervicovaginal fluid (CVF). In residual aqueous CVF, polar metabolites produced biochemistry process were derivatized using methoxyamine and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), and non-targeted analysis were conducted. Nine SCFAs were quantified, and 58 polar metabolites were detected in 90 clinical samples using gas chromatography/mass spectrometry (GC/MS). The criteria of statistical analysis and detection rate of clinical sample for development of PTB biomarkers were presented, and 19 biomarkers were selected based on it, consisting of 1 SCFA, 2 organic acids, 4 amine compounds, and 12 amino acids. In addition, the model was evaluated as a suitable indicator for predicting PTB without distinction between sample collection time. We hope that the developed biomarkers based on microbiota-derived metabolites could provide useful diagnostic biomarkers for actual patients and pre-pregnancy.

The amniotic fluid proteome predicts imminent preterm delivery in asymptomatic women with a short cervix

Preterm birth, the leading cause of perinatal morbidity and mortality, is associated with increased risk of short- and long-term adverse outcomes. For women identified as at risk for preterm birth attributable to a sonographic short cervix, the determination of imminent delivery is crucial for patient management. The current study aimed to identify amniotic fluid (AF) proteins that could predict imminent delivery in asymptomatic patients with a short cervix. This retrospective cohort study included women enrolled between May 2002 and September 2015 who were diagnosed with a sonographic short cervix (< 25 mm) at 16–32 weeks of gestation. Amniocenteses were performed to exclude intra-amniotic infection; none of the women included had clinical signs of infection or labor at the time of amniocentesis. An aptamer-based multiplex platform was used to profile 1310 AF proteins, and the differential protein abundance between women who delivered within two weeks from amniocentesis, and those who did not, was determined. The analysis included adjustment for quantitative cervical length and control of the false-positive rate at 10%. The area under the receiver operating characteristic curve was calculated to determine whether protein abundance in combination with cervical length improved the prediction of imminent preterm delivery as compared to cervical length alone. Of the 1,310 proteins profiled in AF, 17 were differentially abundant in women destined to deliver within two weeks of amniocentesis independently of the cervical length (adjusted p-value < 0.10). The decreased abundance of SNAP25 and the increased abundance of GPI, PTPN11, OLR1, ENO1, GAPDH, CHI3L1, RETN, CSF3, LCN2, CXCL1, CXCL8, PGLYRP1, LDHB, IL6, MMP8, and PRTN3 were associated with an increased risk of imminent delivery (odds ratio > 1.5 for each). The sensitivity at a 10% false-positive rate for the prediction of imminent delivery by a quantitative cervical length alone was 38%, yet it increased to 79% when combined with the abundance of four AF proteins (CXCL8, SNAP25, PTPN11, and MMP8). Neutrophil-mediated immunity, neutrophil activation, granulocyte activation, myeloid leukocyte activation, and myeloid leukocyte-mediated immunity were biological processes impacted by protein dysregulation in women destined to deliver within two weeks of diagnosis. The combination of AF protein abundance and quantitative cervical length improves prediction of the timing of delivery compared to cervical length alone, among women with a sonographic short cervix.

Impact of Preoperative Cervical Length on Pregnancy Outcome in Twin-Twin Transfusion Syndrome

OBJECTIVE

To evaluate the impact of preoperative cervical length on pregnancy outcome in monochorionic diamniotic twin pregnancies complicated by twin-twin transfusion syndrome that underwent laser surgery or cord occlusion.

MATERIALS AND METHODS

Retrospective study of 330 patients stratified by preoperative cervical length (≥25 mm, 16-24 mm,≤15 mm). Maternal characteristics, operative data, and pregnancy outcomes were compared between the cervical length groups as well as between the subgroups of patients with a cervical length≤15 mm according to management (expectant vs. cerclage).

RESULTS

A preoperative cervical length≥25 mm was observed in 82% (n=271) of cases, 16-24 mm in 9% (n=29), and≤15 mm in 9% (n=30). Patients with a preoperative cervical length≤15 mm showed shorter median procedure-to-delivery interval (5.5 weeks vs. 11.6 (16-24 mm) vs. 13.0 (≥25 mm); p<0.001); lower median gestational age at delivery (29.5 weeks vs. 34.3 (16-24 mm) vs. 33.4 (≥25 mm); p<0.001); higher rate of preterm delivery<32 weeks (78 vs. 20% (16-24 mm) vs. 31% (≥25 mm); p<0.001); and lower neonatal survival rate of at least one twin (70 vs. 88% (16-24 mm) vs. 93% (≥25 mm); p<0.001). Outcome of patients with a preoperative cervical length≤15 mm was similar regardless of management.

CONCLUSION

Monochorionic diamniotic twin pregnancies complicated by twin-twin transfusion syndrome with a preoperative cervical length≤15 mm showed a higher rate of preterm delivery<32 weeks and lower neonatal survival. The role of a cervical cerclage remains unclear.

Shear wave elastography: the relationship of the cervical stiffness with gestational age and cervical length- a feasibility study

OBJECTIVES

To standardize the measurement of shear wave elastography for assessment of cervical stiffness and its relationship with gestational age and cervical length.

METHODS

A prospective cross-sectional study was conducted from September 2017 to March 2019. Data from 125 unselected women (at 11-13 + 6, 18-22 and 24-28 weeks' gestation) and 55 high-risk women were analyzed for the study. Six regions of interest were evaluated for cervical elastography in the mid-sagittal position by transvaginal ultrasound. Statistical analyses were performed using R statistical language in R-studio. Delivery outcomes were recorded for each patient.

RESULTS

The shear wave elastography was feasible with good intraoperator and interoperator reproducibility. The endocervical canal and anterior lip internal position had the highest reproducibility (ICC-0.82, 0.75). Shear wave speed was significantly higher in all internal os regions than the external os. There was a statistically significant negative linear relationship of shear wave speed with the gestational age. There was a weak positive relationship between shear wave speed and cervical length. There was no difference between pregnancies with and without spontaneous preterm delivery in shear wave speed measurements and cervical length, although numbers were small for statistical analysis. The internal os of the large loop excision of the transformation zone group was stiffer than the normal population.

CONCLUSION

Cervical elastography is feasible and effectively evaluates the tensile properties of the cervix during pregnancy. The most reproducible measurements were obtained at the anterior lip of the internal cervical os. Combining evaluation of cervical elasticity and length might further improve the identification of women at risk of preterm delivery. Currently, technical issues hinder the practical application of shear wave elastography in the clinical setting and require further research and development of the imaging modality.

Study protocol to quantify the genetic architecture of sonographic cervical length and its relationship to spontaneous preterm birth

INTRODUCTION

A short cervix (cervical length <25 mm) in the midtrimester (18-24 weeks) of pregnancy is a powerful predictor of spontaneous preterm delivery. Although the biological mechanisms of cervical change during pregnancy have been the subject of extensive investigation, little is known about whether genes influence the length of the cervix, or the extent to which genetic factors contribute to premature cervical shortening. Defining the genetic architecture of cervical length is foundational to understanding the aetiology of a short cervix and its contribution to an increased risk of spontaneous preterm delivery.

METHODS/ANALYSIS

The proposed study is designed to characterise the genetic architecture of cervical length and its genetic relationship to gestational age at delivery in a large cohort of Black/African American women, who are at an increased risk of developing a short cervix and delivering preterm. Repeated measurements of cervical length will be modelled as a longitudinal growth curve, with parameters estimating the initial length of the cervix at the beginning of pregnancy, and its rate of change over time. Genome-wide complex trait analysis methods will be used to estimate the heritability of cervical length growth parameters and their bivariate genetic correlation with gestational age at delivery. Polygenic risk profiling will assess maternal genetic risk for developing a short cervix and subsequently delivering preterm and evaluate the role of cervical length in mediating the relationship between maternal genetic variation and gestational age at delivery.

ETHICS/DISSEMINATION

The proposed analyses will be conducted using deidentified data from participants in an IRB-approved study of longitudinal cervical length who provided blood samples and written informed consent for their use in future genetic research. These analyses are preregistered with the Center for Open Science using the AsPredicted format and the results and genomic summary statistics will be published in a peer-reviewed journal.

Evaluation of midtrimester cervical length thresholds for the prediction of spontaneous preterm birth

INTRODUCTION

To estimate the optimal midtrimester cervical length (CL) threshold for the prediction of spontaneous preterm birth (sPTB) in asymptomatic pregnant women.

MATERIAL AND METHODS

This is a prospective observational cohort study including asymptomatic women with singleton pregnancies who underwent CL measurement by transabdominal and/or transvaginal ultrasound between 19°^/7 and 21^6/7 weeks of gestation. All CL ≤30 mm from transabdominal ultrasound were confirmed by transvaginal ultrasound. Primary outcomes were sPTB <35 and <37 weeks.

RESULTS

Out of 3,449 participants, 28 (0.8%) had a sPTB before 35 weeks and 99 (2.9%) had a sPTB before 37 weeks. Receiver operating characteristics (ROC) curves suggest that a cut-off of 30 mm was the optimal CL to predict sPTB before 35 weeks (sensitivity: 43%; specificity: 97%) and sPTB before 37 weeks (sensitivity: 21%; specificity: 97%). While a CL <25 mm was an important risk factor for sPTB before 35 weeks (relative risk: 31; 95% confidence interval: 13-73), women with a CL between 25 and 30 mm were also at greater risk (relative risk: 12; 95% confidence interval: 4 - 35) compared to women with CL ≥30 mm.

DISCUSSION

A midtrimester CL <30 mm should be considered to identify women at high-risk of sPTB.

Revisions to mid-pregnancy cervical length reference range for preterm birth screening among singleton pregnancies in Taiwan - 10 years' experiences

OBJECTIVE

Our study aimed to build a normal reference range for routine mid-pregnancy cervical length screening for preterm birth (PTB) based on a large cross-section of Taiwanese singleton pregnancies. Based on our reference range findings, we aim to develop a Z-score and centile calculator.

MATERIALS AND METHODS

We performed a retrospective analysis of the routine mid-trimester cervical length measurement in low-risk singleton pregnancies (without known abnormal growth or karyotype, congenital malformation, history of preterm birth due to preterm premature rupture of the membranes, or history of cervical cerclage treatment). From November 2008 to June 2018, the cervical lengths of 51,644 Taiwanese low-risk pregnant women were measured by experienced sonographers via transvaginal ultrasound during second trimester fetal anatomical screening at 20-24 weeks of gestation. Kolmogorov-Smirnov test was used to assess the normality of the distribution. Cole's lambda, mu, sigma (LMS) method was applied to build mid-pregnancy cervical length reference range and calculate Z-scores. Cut-off values of 2.5, 2.0 and 1.5 cm were used to evaluate the number of pregnancies considered high-risk for PTB.

RESULTS

Kolmogorov-Smirnov test showed that the cervical length measurements did not follow a normal distribution (<0.001). Reference range constructed by LMS method was presented in our study. Mean cervical length was 3.82 cm (SD = 0.62 cm). Overall, less than 0.3% of women had a cervical length shorter than 1.5 cm.

CONCLUSION

We are providing an open access calculator for z-score and centile calculation for use in clinical practice for assessing how CL measurement compares in normally developing singleton pregnancies. Further investigation is needed to determine if Z-scores can better assess risk for PTB compared to fixed cut-offs. Since Z-scores are used to assess large deviations from normal development, they may be a useful tool for risk assessment and can be the basis for future standardized screening protocol in Taiwan.

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.

Cerclage in singleton gestations with an extremely short cervix (≤10 mm) and no history of spontaneous preterm birth

BACKGROUND

Data regarding the efficacy of a cervical cerclage for preterm birth prevention in patients with a short cervix and no history of spontaneous preterm birth are limited and inconclusive.

OBJECTIVE

This study aimed to determine whether cervical cerclage is associated with an increased time interval to delivery in asymptomatic patients with singleton pregnancies with an extremely short cervical length (≤10 mm) and no history of spontaneous preterm birth.

STUDY DESIGN

This was a multicenter retrospective cohort study of asymptomatic patients with singleton pregnancies with a cervical length of ≤10 mm between 16 and 23 weeks' gestation from January 2014 to December 2019. Patients with previous spontaneous preterm birth, symptoms of preterm labor, cervical dilation of >1 cm, pessary, major fetal structural malformations, or missing data were excluded from the study. The primary outcome of time interval from diagnosis to delivery was compared between those who had a cervical cerclage after diagnosis and those who did not. The secondary outcomes included gestational age at delivery and adverse neonatal outcomes. Moreover, a subgroup analysis of all outcomes in patients already being treated with vaginal progesterone in each group was performed. Statistical analysis included chi-square and Wilcoxon rank-sum tests and a multivariate Cox proportional hazard regression for time interval to delivery.

RESULTS

Of the 90 patients included in the study, 52 (57.8%) had cervical cerclage, of which 35 (67.3%) were already being treated with progesterone. Moreover, 38 patients (42.2%) did not have cervical cerclage, of which 21 (55.3%) were already being treated with progesterone. Patients in the cervical cerclage group had an earlier gestational age (21.0 vs 22.0 weeks' gestation; P≤.001) and shorter cervical length (5 vs 7 mm; P=.002) at the diagnosis of a short cervix (cervical length≤10 mm) than those who did not have a cerclage. Cervical cerclage was associated with a longer time interval to delivery (17.0 vs 15.0 weeks; P=.02) and lower hazard of earlier delivery after diagnosis (adjusted hazard ratio, 0.61; 95% confidence interval, 0.38-0.99; P=.04) than no cerclage, after accounting for gestational age and cervical length at diagnosis. In patients already treated with progesterone, cervical cerclage was also associated with a longer time interval to delivery (17.0 vs 13.1 weeks; P=.01) and a lower hazard of earlier delivery after diagnosis (adjusted hazard ratio, 0.49; 95% confidence interval, 0.27-0.87; P=.02) compared to those with no cerclage. Late preterm birth was less common in patients with a cervical cerclage compared with those with no cervical cerclage (11.5% vs 31.6%; P=.03).

CONCLUSION

Cervical cerclage should be considered in asymptomatic patients with an extremely short cervical length (≤10 mm) and no history of spontaneous preterm birth.

The Impact of Routine Transvaginal Ultrasound Measurement of the Cervical Length on the Prediction of Preterm Birth: A Retrospective Study in a Tertiary Hospital

Preterm birth (PTB) is a major obstetric problem associated with high rates of neonatal morbidity and mortality. The prevalence of PTB has not changed in the last decade; thus, the establishment of a screening test and effective treatment are warranted. Transvaginal ultrasound measurement of the cervical length (TUCL) has been proposed as an effective method to screen pregnant women at a higher risk of experiencing PTB.

OBJECTIVE

 To evaluate the applicability and usefulness of second-trimester TUCL to predict PTB in a cohort of Portuguese pregnant women.

METHODS

 Retrospective cross-sectional cohort study including all singleton pregnant women who performed their second-trimester ultrasound (between weeks 18 and 22 + 6 days) from January 2013 to October 2017 at Centro Hospitalar Universitário São João.

RESULTS

 Our cohort included 4,481 women. The prevalence of spontaneous PTB was of 4.0%, with 0.7% occurring before the 34th week of gestation. The mean TUCL was of 33.8 mm, and percentiles 3, 5 and 10 corresponded to TUCLs of 25.0 mm, 27.0 mm and 29.0 mm respectively. The multiple logistic regression analysis, including maternal age, previous PTB and cervical surgery showed a significant negative association between TUCL and PTB, with an odds ratio (OR) of 0.92 (95% confidence interval [95%CI]: 0.90-0.95; p < 0.001). The use of a TUCL of 20 mm is the best cut-off, when compared with the 25-mm cut-off, improving the prediction of risk.

CONCLUSION

 The present study showed an inverse association between TUCL and PTB, and that the inclusion of other risk factors like maternal age, previous PTB and cervical surgery can improve the screening algorithm. Furthermore, it emphasizes that the TUCL cut-off that defines short cervix can differ according to the population.

Can sonographic changes in cervical length during pregnancy predict the need for cervical ripening in term pregnancies?

PURPOSE

To evaluate the effect of changes in sonographic cervical length (CL) measured at 14-16 and 21-24 weeks of gestation, on cervical ripening in term pregnancies.

METHODS

This retrospective, cohort study included term pregnancies with CL measured with transvaginal sonography (CL₁ at 14-16 weeks gestation and CL₂ at 21-24 weeks). History of preterm labor, multiple gestations, planned caesarean section, fetal anomalies and stillbirths were excluded. Participants were grouped based on ≥ 10% vs. < 10% CL shortening between measurements. The primary outcome was whether cervical shortening < 10% between CL₁ and CL₂ was associated with increased use of cervical ripening. Secondary outcomes were gestational age at delivery, delivery mode and birthweight.

RESULTS

Among 267 women who met the inclusion criteria, CL decreased ≥ 10% between scans in 70 (26.3%) and < 10% in 197 (73.7%). Baseline characteristics were similar between groups. Fewer women with ≥ 10% shortening between scans, underwent cervical ripening (7.1% vs. 16.8%, p < 0.05). In addition, in the ≥ 10% group, although CL₂ was in the normal range, it was shorter than in the < 10% group (34.3 ± 6.7 mm vs. 40.1 ± 6.4 mm, p < 0.01).

CONCLUSION

Decrease in cervical length > 10% between 14-16 and 21-24-weeks' gestation is associated with lower use of cervical ripening at term.

Personalized assessment of cervical length improves prediction of spontaneous preterm birth: a standard and a percentile calculator

BACKGROUND

A sonographic short cervix (length <25 mm during midgestation) is the most powerful predictor of preterm birth. Current clinical practice assumes that the same cervical length cutoff value should apply to all women when screening for spontaneous preterm birth, yet this approach may be suboptimal.

OBJECTIVE

This study aimed to (1) create a customized cervical length standard that considers relevant maternal characteristics and gestational age at sonographic examination and (2) assess whether the customization of cervical length evaluation improves the prediction of spontaneous preterm birth.

STUDY DESIGN

This retrospective analysis comprises a cohort of 7826 pregnant women enrolled in a longitudinal protocol between January 2006 and April 2017 at the Detroit Medical Center. Study participants met the following inclusion criteria: singleton pregnancy, ≥1 transvaginal sonographic measurements of the cervix, delivery after 20 weeks of gestation, and available relevant demographics and obstetrical history information. Data from women without a history of preterm birth or cervical surgery who delivered at term without progesterone treatment (N=5188) were used to create a customized standard of cervical length. The prediction of the primary outcome, spontaneous preterm birth at <37 weeks of gestation, was assessed in a subset of pregnancies (N=7336) that excluded cases with induced labor before 37 weeks of gestation. Area under the receiver operating characteristic curve and sensitivity at a fixed false-positive rate were calculated for screening at 20 to 23 6/7, 24 to 27 6/7, 28 to 31 6/7, and 32 to 35 6/7 weeks of gestation in asymptomatic patients. Survival analysis was used to determine which method is better at predicting imminent delivery among symptomatic women.

RESULTS

The median cervical length remained fundamentally unchanged until 20 weeks of gestation and subsequently decreased nonlinearly with advancing gestational age among women who delivered at term. The effects of parity and maternal weight and height on the cervical length were dependent on the gestational age at ultrasound examination (interaction, P<.05 for all). Parous women had a longer cervix than nulliparous women, and the difference increased with advancing gestation after adjusting for maternal weight and height. Similarly, maternal weight was nonlinearly associated with a longer cervix, and the effect was greater later in gestation. The sensitivity at a 10% false-positive rate for prediction of spontaneous preterm birth at <37 weeks of gestation by a short cervix ranged from 29% to 40% throughout pregnancy, yet it increased to 50%, 50%, 53%, and 54% at 20 to 23 6/7, 24 to 27 6/7, 28 to 31 6/7, and 32 to 35 6/7 weeks of gestation, respectively, for a low, customized percentile (McNemar test, P<.001 for all). When a cervical length <25 mm was compared to the customized screening at 20 to 23 6/7 weeks of gestation by using a customized percentile cutoff value that ensured the same negative likelihood ratio for both screening methods, the customized approach had a significantly higher (about double) positive likelihood ratio in predicting spontaneous preterm birth at <33, <34, <35, <36, and <37 weeks of gestation. Among symptomatic women, the difference in survival between women with a customized cervical length percentile of ≥10th and those with a customized cervical length percentile of <10th was greater than the difference in survival between women with a cervical length ≥25 mm and those with a cervical length <25 mm.

CONCLUSION

Compared to the use of a cervical length <25 mm, a customized cervical length assessment (1) identifies more women at risk of spontaneous preterm birth and (2) improves the distinction between patients at risk for impending preterm birth in those who have an episode of preterm labor.

Cervical length varies considering different populations and gestational outcomes: Results from a systematic review and meta-analysis

BACKGROUND

The uterine cervical length is an important risk factor for preterm birth. The aim of this study was to assess cervical length distribution in women with singleton pregnancies, measured by transvaginal ultrasound between 16 and 24 weeks, and its association with population characteristics.

MATERIALS AND METHODS

We searched electronic databases and other sources for studies published from April 1, 1990 to July 21, 2020. Of the 2019 retrieved publications, full-text versions of 137 articles were considered. We included 77 original articles that reported cervical length measurements of 363,431 women. The main aim of this study was to identify the pattern of cervical length in different populations. We collected demographic and clinical data concerning the population, in addition to information regarding the ultrasound examination and cervical length measurement. Regarding study bias, 56 were at low risk of bias and 21 were at medium risk of bias.

RESULTS

The meta-analysis included 57 articles with data from 158,346 women. The mean cervical length was 37.96. mm (95% CI [36.68, 39.24]). Cervical length was shorter in women from Africa and Asia, in those from low-income countries, with a lower body weight, and in those who delivered before 37 gestational weeks. We found that the cervical length from pooled studies is longer than that usually discussed in the literature. Regarding limitations, we had difficulty assessing our main variable because there was no consistent pattern in the way authors reported cervical length measurement. Another limitation was the great heterogeneity between studies.

CONCLUSIONS

The use of a single cutoff value to define a short cervix diagnosis, an important risk factor for preterm birth, may not be correct and cervical length must be considered according to maternal population characteristics. Future studies should identify different specific curves and cutoff values for cervical length in different populations. This meta-analysis was registered in the PROSPERO database under CRD42017070246 at https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=70246.

Development and validation of a model for individualized prediction of cervical insufficiency risks in patients undergoing IVF/ICSI treatment

BACKGROUND

Women who conceived with in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) are more likely to experience adverse pregnancy outcomes than women who conceived naturally. Cervical insufficiency (CI) is one of the important causes of miscarriage and premature birth, however there is no published data available focusing on the potential risk factors predicting CI occurrence in women who received IVF/ICSI treatment. This study aimed to identify the risk factors that could be integrated into a predictive model for CI, which could provide further personalized and clinically specific information related to the incidence of CI after IVF/ICSI treatment.

PATIENTS AND METHODS

This retrospective study included 4710 patients who conceived after IVF/ICSI treatment from Jan 2011 to Dec 2018 at a public university hospital. The patients were randomly divided into development (n = 3108) and validation (n = 1602) samples for the building and testing of the nomogram, respectively. Multivariate logistic regression was developed on the basis of pre-pregnancy clinical covariates assessed for their association with CI occurrence.

RESULTS

A total of 109 patients (2.31%) experienced CI among all the enrolled patients. Body mass index (BMI), basal serum testosterone (T), gravidity and uterine length were associated with CI occurrence. The statistical nomogram was built based on BMI, serum T, gravidity and uterine length, with an area under the curve (AUC) of 0.84 (95% confidence interval: 0.76-0.90) for the developing cohort. The AUC for the validation cohort was 0.71 (95% confidence interval: 0.69-0.83), showing a satisfactory goodness-of-fit and discrimination ability in this nomogram.

CONCLUSION

The user-friendly nomogram which graphically represents the risk factors and a pre-pregnancy predicted tool for the incidence of CI in patients undergoing IVF/ICSI treatment, provides a useful guide for medical staff on individualized decisions making, where preventive measures could be carried out during the IVF/ICSI procedure and subsequent pregnancy.

Pregnancy-specific transcriptional changes upon endotoxin exposure in mice

Objectives Pregnant women are more susceptible to certain infections; however, this increased susceptibility is not fully understood. Herein, systems biology approaches were utilized to elucidate how pregnancy modulates tissue-specific host responses to a bacterial product, endotoxin. Methods Pregnant and non-pregnant mice were injected with endotoxin or saline on 16.5 days post coitum (n=8-11 per group). The uterus, cervix, liver, adrenal gland, kidney, lung, and brain were collected 12 h after injection and transcriptomes were measured using microarrays. Heatmaps and principal component analysis were used for visualization. Differentially expressed genes between groups were assessed using linear models that included interaction terms to determine whether the effect of infection differed with pregnancy status. Pathway analysis was conducted to interpret gene expression changes. Results We report herein a multi-organ atlas of the transcript perturbations in pregnant and non-pregnant mice in response to endotoxin. Pregnancy strongly modified the host responses to endotoxin in the uterus, cervix, and liver. In contrast, pregnancy had a milder effect on the host response to endotoxin in the adrenal gland, lung, and kidney. However, pregnancy did not drastically affect the host response to endotoxin in the brain. Conclusions Pregnancy imprints organ-specific host immune responses upon endotoxin exposure. These findings provide insight into the host-response against microbes during pregnancy.

Cellular immune responses in amniotic fluid of women with a sonographic short cervix

Objectives A sonographic short cervix is one of the strongest predictors of preterm delivery. However, the cellular immune composition of amniotic fluid in women with a short cervix has not yet been described. Herein, we determined cellular and soluble immune responses in amniotic fluid from pregnant women with a mid-trimester asymptomatic short cervix. Methods Amniotic fluid samples (n=77) were collected from asymptomatic women with a cervical length between 15 and 25 mm (n=36, short cervix) or ≤15 mm (n=41, severely short cervix) diagnosed by ultrasound. Flow cytometry and multiplex measurement of cytokines/chemokines were performed. Results (1) The cellular immune composition of amniotic fluid did not differ between women with a severely short cervix (≤15 mm) and those with a short cervix 15-25 mm; (2) amniotic fluid concentrations of multiple cytokines/chemokines were higher in women with a severely short cervix (≤15 mm) than in those with a short cervix 15-25 mm; (3) the cellular immune composition of amniotic fluid did not differ between women with a severely short cervix (≤15 mm) who ultimately underwent preterm delivery and those who delivered at term; and (4) amniotic fluid concentrations of IL-2, but not other immune mediators, were increased in women with a severely short cervix (≤15 mm) who ultimately delivered preterm compared to those who delivered at term. Conclusions Women with a severely short cervix (≤15 mm) have increased concentrations of pro-inflammatory mediators in the amniotic cavity; yet, these do not translate to changes in the cellular immune response.

Cervical pessary for preterm twin pregnancy in women with a short cervix

Objective

We aimed to evaluate the effectiveness of cervical pessary for extending twin pregnancy in women with a short cervix.

Methods

Between January 2014 and March 2019, the use of a cervical pessary for twin pregnancy in women with a cervical length of ≤15 mm was investigated between 16 and 28 weeks of gestation. We included women with a shortened cervix after a cerclage procedure and visible fetal membranes and cervical dilatation. Thirteen patients underwent pessary insertion and were matched with a control group of 15 patients. Pregnancy and neonatal outcomes were compared between the groups. We excluded women with major fetal anomalies discovered before or after birth and known placenta previa.

Results

Women who underwent pessary insertion were diagnosed with a short cervix (0.65±0.47 vs. 0.66±0.51 cm in the pessary and control groups, respectively; P=0.957) at a gestational age similar to that of the controls (23.29 vs. 25.14 weeks, P=0.294). There was no significant difference in gestational age at delivery between them (33.29 vs. 27.29 weeks in the pessary and control groups, respectively, P=0.058). The pessary group had a longer interval between the diagnosis and delivery than the control group (60.7±28.3 vs. 22.6±24.5 days, P=0.001). The number of adverse neonatal outcomes was significantly lower in the pessary group (n=7; 28.0%) than in the control group (n=14; 58.3%; P=0.032).

Conclusion

The use of a cervical pessary may prolong gestation in twin pregnancies in women with an extremely short cervix until viable gestational age.

The role of noninvasive diagnostic imaging in monitoring pregnancy and detecting patients at risk for preterm birth: a review of quantitative approaches

Preterm birth (PTB) is the leading cause of neonatal morbidity and mortality worldwide. The ability to predict patients at risk for preterm birth remains a major health challenge. The currently available clinical diagnostics such as cervical length and fetal fibronectin may detect only up to 30% of patients who eventually experience a spontaneous preterm birth. This paper reviews ongoing efforts to improve the ability to conduct a risk assessment for preterm birth. In particular, this work focuses on quantitative methods of imaging using ultrasound-based techniques, magnetic resonance imaging, and optical imaging modalities. While ultrasound imaging is the major modality for preterm birth risk assessment, a summary of efforts to adopt other imaging modalities is also discussed to identify the technical and diagnostic limits associated with adopting them in clinical settings. We conclude the review by proposing a new approach using combined photoacoustic, ultrasound, and elastography as a potential means to better assess cervical tissue remodeling, and thus improve the detection of patients at-risk of PTB.

Emergency cerclage following a standardized protocol offers an effective and safe therapeutic option for women with high risk for prematurity - a retrospective monocentric cohort study on 130 pregnancies and 155 neonates

Objective: To present emergency cerclage (EC) as a safe and effective therapeutic option for prevention of prematurity in women with advanced cervical dilation in second-trimester pregnancy. It is focused on seemingly futile situations like cervical dilation >5 cm, bulging membranes and multifetal pregnancies. The outcomes of interest are the prolongation of pregnancy, gestational age at delivery and neonatal morbidity and mortality related to distinct risk factors.Study design: Retrospective monocentric cohort study involving 130 pregnancies (105 single and 25 twin pregnancies) and 155 neonates by using a standardized protocol. Women between 18 and 28 gestational weeks with cervical shortening of <10 mm + cervical dilation >2 cm and/or bulging membranes were included. Analyses of maternal and neonatal parameters were done by chart review.Results: The medium gestational age at delivery was 35 5/7 week with a medium interval from cerclage placement to delivery of 83 days. Overall, 46.5% (72/155) neonates were born beyond 37 weeks, extreme prematurity of less than 28 gestational weeks was observed in 14.8% (23/155), no miscarriage before 22 weeks was documented. The neonatal mortality was 1.9% (3/155). Neonatal deaths and morbidity was related to severe prematurity exclusively. The association of amnion-infection syndromes and failing therapy was significantly with respect to bulging membranes and advanced cervical dilation >5 cm.Conclusions: Even in futile cases EC can be an option to save the pregnancy and prevent severe prematurity. However, a standardized protocol is imminent for successful therapy and every indication has to be a case by case decision.

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.

Mechanics of cervical remodelling: insights from rodent models of pregnancy

The uterine cervix undergoes a complex remodelling process during pregnancy, characterized by dramatic changes in both extracellular matrix (ECM) structure and mechanical properties. Understanding the cervical remodelling process in a term or preterm birth will aid efforts for the prevention of preterm births (PTBs), which currently affect 14.8 million babies annually worldwide. Animal models of pregnancy, particularly rodents, continue to provide valuable insights into the cervical remodelling process, through the study of changes in ECM structure and mechanical properties at defined gestation time points. Currently, there is a lack of a collective, quantitative framework to relate the complex, nonlinear mechanical behaviour of the rodent cervix to changes in ECM structure. This review aims to fill this gap in knowledge by outlining the current understanding of cervical remodelling during pregnancy in rodent models in the context of solid biomechanics. Here we highlight the collective contribution of multiple mechanical studies which give evidence that cervical softening coincides with known ECM changes throughout pregnancy. Taken together, mechanical tests on tissue from pregnant rodents reveal the cervix's remarkable ability to soften dramatically during gestation to allow for a compliant tissue that can withstand damage and can dissipate mechanical loads.

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

OBJECTIVE

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

DESIGN

Prospective cohort study.

SETTING

A large UK teaching hospital.

POPULATION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Photoacoustic imaging of the uterine cervix to assess collagen and water content changes in murine pregnancy

The uterine cervix plays a central role in the maintenance of pregnancy and in the process of parturition. Cervical remodeling involves dramatic changes in extracellular matrix composition and, in particular, of collagen and water content during cervical ripening (a term that describes the anatomical, biochemical, and physiologic changes in preparation for labor). Untimely cervical ripening in early gestation predisposes to preterm labor and delivery, the leading cause of infant death worldwide. Inadequate ripening of the cervix is associated with failure of induction or prolonged labor. The current approach to evaluate the state of the cervix relies on digital examination and sonographic examination. Herein, we present a novel imaging method that combines ultrasound (US) and photoacoustic (PA) techniques to evaluate cervical remodeling by assessing the relative collagen and water content of this organ. The method was tested in vitro in extracted collagen phantoms and ex vivo in murine cervical tissues that were collected in mid-pregnancy and at term. We report, for the first time, that our imaging approach provides information about the molecular changes in the cervix at different gestational ages. There was a strong correlation between the results of PA imaging and the histological assessment of the uterine cervix over the course of gestation. These findings suggest that PA imaging is a powerful method to assess the biochemical composition of the cervix and open avenues to non-invasively investigate the composition of this organ, which is essential for reproductive success.

The earlier the gestational age, the greater the intensity of the intra-amniotic inflammatory response in women with preterm premature rupture of membranes and amniotic fluid infection by Ureaplasma species

Objectives To determine the relationship between the intensity of the intra-amniotic inflammatory response and the gestational age at the time of diagnosis in cases with preterm premature rupture of membranes (PROM) and intra-amniotic infection caused by Ureaplasma spp. Methods A retrospective cohort study was conducted which included 71 women with preterm PROM and a positive amniotic fluid culture with Ureaplasma spp. Women with mixed intra-amniotic infections were excluded. The study population was classified into three groups according to gestational age: group 1, <26 weeks (extreme preterm PROM, n = 17); group 2, 26.0-33.9 weeks (moderate preterm PROM, n = 39); group 3, 34.0-36.9 weeks (late preterm PROM, n = 15). The intensity of the intra-amniotic and maternal inflammatory response was compared among the three groups. The intensity of the intra-amniotic inflammatory response was assessed by the concentration of amniotic fluid matrix metalloproteinase-8 (MMP-8) and white blood cell (WBC) count. The maternal inflammatory response was assessed by the concentration of C-reactive protein (CRP) and WBC count in maternal blood at the time of amniocentesis. Results (1) The median values of amniotic fluid MMP-8 concentration and WBC count were the highest in the extreme preterm PROM group and the lowest in the late preterm PROM group (P < 0.001 and P = 0.01, respectively); (2) the intensity of the maternal inflammatory response measured by maternal blood WBC count and CRP concentration was not significantly associated with gestational age at the time of diagnosis. Conclusion The earlier the gestational age at the time of PROM, the higher the intensity of the intra-amniotic inflammatory response in women with preterm PROM and intra-amniotic infection caused by Ureaplasma spp.

HIV serostatus, viral load, and midtrimester cervical length in a Zambian prenatal cohort

OBJECTIVE

To evaluate whether maternal HIV serostatus and plasma viral load (VL) are associated with midtrimester cervical length (CL).

METHODS

The Zambian Preterm Birth Prevention Study (ZAPPS) is an ongoing prospective cohort that began enrolling in Lusaka in August 2015. Pregnant women undergo ultrasound to determine gestational age and return for CL measurement at 16-28 weeks. We evaluated crude and adjusted associations between dichotomous indicators and short cervix (≤2.5 cm) via logistic regression, and between VL and CL as a continuous variable via linear regression.

RESULTS

This analysis includes 1171 women enrolled between August 2015 and September 2017. Of 294 (25.1%) HIV-positive women, 275 (93.5%) had viral load performed close to CL measurement; of these, 148 (53.8%) had undetectable virus. Median CL was 3.6 cm (IQR 3.5-4.0) and was similar in HIV-infected (3.7 cm, IQR 3.5-4.0) versus uninfected (3.6 cm, IQR 3.5-4.0) participants (P=0.273). The odds of short CL were similar by HIV serostatus (OR 0.64; P=0.298) and detectable VL among those infected (OR 2.37, P=0.323). We observed no association between log VL and CL via linear regression (-0.12 cm; P=0.732).

CONCLUSION

We found no evidence of association between HIV infection and short CL.

A high concentration of fetal fibronectin in cervical secretions increases the risk of intra-amniotic infection and inflammation in patients with preterm labor and intact membranes

Objective To determine whether the risk of intra-amniotic infection/inflammation and spontaneous preterm delivery (SPTD) varies as a function of the concentration of cervical fetal fibronectin (fFN) in patients with preterm labor and intact membranes. Methods This prospective study included 180 patients with preterm labor and intact membranes who had a sample collected for quantitative fFN measurement and underwent amniocentesis. Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas. Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. Results (1) The prevalence of intra-amniotic infection/inflammation and SPTD within 7 days was 32.2% (58/180) and 33.9% (61/178), respectively; (2) The higher the fFN concentration, the greater the risk of intra-amniotic infection/inflammation and SPTD within 7 days (P<0.001, respectively); (3) An fFN concentration 150 ng/mL had a better diagnostic performance than an fFN 50 ng/mL in the identification of intra-amniotic infection/inflammation and SPTD within 7 days; (4) Among the patients with an fFN <50 ng/mL, intra-amniotic infection/inflammation was identified in 7.6% (6/79) of patients and 66.7% (4/6) delivered within 7 days. Conclusion The higher the concentration of fFN, the greater the risk of intra-amniotic infection/inflammation and SPTD in patients with preterm labor and intact membranes.

Universal cervical length screening with a cervicometer to prevent preterm birth <34 weeks: a decision and economic analysis

Background: Preterm birth is a leading cause of neonatal morbidity and mortality worldwide; evidence-based strategies to decrease preterm birth are desperately needed.Objective: The purpose of this study was to estimate which of three strategies for screening for shortened cervix in asymptomatic low-risk women is the most cost-effective in terms of prevention of preterm birth and associated morbidity.Study design: A decision analysis model was developed from available published evidence comparing three strategies in screening asymptomatic low-risk women for shortened cervix: (1) cervicometer with subsequent referral for transvaginal ultrasound, (2) transvaginal ultrasound screening, and (3) no screening. The cost and effectiveness of each strategy was assessed in terms of quality-adjusted life-years (QALYs), and cost in US dollars.Results: Screening with a cervicometer with referral was the most cost-effective strategy and represented a savings of $999.65 ($11,617.28 versus $12,616.93) over screening with ultrasound, and a savings of $15,601.62 ($11,617.28 versus $27,218.90) over no screening. Costs for outcomes ranged from $3528 for a healthy neonate ≥34 weeks to $717,467.5 for a neonate <34 weeks with severe morbidity. The cervicometer strategy avoided 11.68 neonatal deaths per 1000 deliveries (3.59 deaths versus 15.27 deaths) compared with no screening, and avoided 0.73 neonatal deaths per 1000 deliveries (3.59 deaths versus 4.32 deaths) compared with ultrasound strategy. The cervicometer strategy prevented 82.44 preterm births per 1000 deliveries (22.56 versus 105.00) compared with no screening, and 5.10 preterm births per 1000 deliveries (22.56 versus 27.66) compared with ultrasound strategy. Per QALY, cervicometer screening cost $386.57, transvaginal ultrasound cost $420.31, and no screening cost $922.73. Sensitivity analyses confirmed the robustness of these findings, including evaluation across the range of quoted transvaginal ultrasound costs ($43-$300).Conclusion: A simulation of universal screening of asymptomatic low-risk women with a cervicometer with subsequent referral for ultrasound for those with a cervix <25 mm is cost-effective and yields the greatest reduction in preterm births at <34 weeks. A risk simulation trial noted that a cervicometer strategy may be more expensive than a universal transvaginal ultrasound strategy, but both are less expensive than a no screening strategy.

Development of a mucoinert progesterone nanosuspension for safer and more effective prevention of preterm birth

Preterm birth (PTB) is a significant global problem, but few therapeutic options exist. Vaginal progesterone supplementation has been demonstrated to reduce PTB rates in women with a sonographic short cervix, yet there has been little investigation into the most effective dose or delivery form. Further, vaginal products like progesterone gel often contain excipients that cause local toxicity, irritation, and leakage. Here, we describe the development and characterization of a mucoinert vaginal progesterone nanosuspension formulation for improved drug delivery to the female reproductive tract. We compare the pharmacokinetics and pharmacodynamics to the clinical comparator progesterone gel in pregnant mice and demonstrate increased vaginal absorption and biodistribution via the uterine first-pass effect. Importantly, the unique plasma progesterone double peak observed in humans, reflecting recirculation from the uterus, was also observed in pregnant mice with vaginal dosing. We adapted a mouse model of progesterone withdrawal that was previously believed to be incompatible with testing the efficacy of exogenous progestins, and are first to demonstrate efficacy in preventing preterm birth with vaginal progesterone in this model. Further, improved vaginal progesterone delivery by the nanosuspension led to increased efficacy in PTB prevention. Additionally, we identified histological and transcriptional evidence of cervical and uterine toxicity with a single vaginal administration of the clinical gel that are absent after dosing with the mucoinert nanosuspension formulation. We demonstrate that a progesterone formulation that is designed for improved vaginal progesterone absorption and vaginal biocompatibility could be more effective for PTB prevention.

McDonald versus modified Shirodkar rescue cerclage in women with prolapsed fetal membranes

Purpose: We compared the efficacy of modified Shirodkar and McDonald rescue cerclage techniques in women with singleton pregnancies.Methods: The study sample included 47 women who presented at two tertiary hospitals in Turkey from 2008 to 2017 and underwent rescue cerclage due to cervical incompetence and cervical dilatation with fetal membranes prolapsed into the vagina. The outcomes were compared by cerclage technique used, Shirodkar or McDonald.Results: The McDonald cerclage was applied in 27 cases, and modified Shirodkar cerclage in 20 cases. A longer cerclage-to-birth interval (83.8 ± 37.6 vs. 63.7 ± 38.9 days) and later gestational age at delivery (33 vs. 31 weeks) were observed with the Shirodkar cerclage, although these differences were not statistically significant (p = .08 and .63, respectively). Both groups had similar delivery rates after 28, 32, and 37 weeks (p = .20, .15, and .25, respectively), whereas the modified Shirodkar technique resulted in a higher rate of live births although these differences were not statistically significant (85% vs. 63%, p = .09).Conclusion: The effects of the McDonald and modified Shirodkar cerclage procedures on prolonging pregnancy and improving the live birth rate were similar. Therefore, either technique can be applied to prevent neonatal loss due to advanced prematurity.

The presence of amniotic fluid sludge in pregnant women with a short cervix: an independent risk of preterm delivery

Objective: To examine whether the presence of amniotic fluid sludge (AFS) could increase the risk of preterm delivery in women with a cervical length (CL) of less than 25 mm.Materials and methods: This is a retrospective cohort study of 110 women who were 14-30 weeks pregnant with a singleton gestation and a CL of less than 25 mm. The primary outcomes were defined as preterm delivery before 34 weeks and preterm delivery before 37 weeks. The secondary outcome was defined as preterm premature rupture of membranes (PPROM) prior to preterm delivery. Risk factors for preterm delivery were defined as AFS, subchorionic hematoma (SCH), history of preterm delivery, CL of less than 20 mm, and CL of less than 15 mm. A univariate analysis was performed to assess the primary and secondary outcomes according to the presence or absence of each risk factor. A multiple logistic regression analysis was performed to evaluate the parameters, using a significance of p < .05 on the univariate analysis to examine whether they were independent risk factors.Results: A significantly increased risk of preterm delivery was found in the group of women with AFS who actually did deliver prior to 34 weeks (p < .001; odds ratio [OR] 6.44; 95% confidence interval [CI] 2.51-16.5), prior to 37 weeks (p = .001; OR 4.46; 95% CI 1.76-11.3), and who had PPROM (p < .001; OR 4.96; 95% CI 2.00-12.3). A multivariate logistic regression analysis was performed in the women with AFS who experienced preterm delivery before 34 weeks, in the women with a CL less than 20 mm, and in the women with a CL less than 15 mm. The results showed that AFS was an independent risk factor for preterm delivery before 34 weeks (p = .001; OR 5.86; 95% CI 2.11-16.3).Conclusion: The presence of AFS was an independent risk factor for preterm delivery before 34 weeks in women with a CL less than 25 mm.

Randomized trial of the efficacy of intravaginal ulinastatin administration for the prevention of preterm birth in women with a singleton pregnancy and both cervical shortening and inflammation of lower genital tract

AIM

To assess the preventive effect on preterm birth of intravaginal ulinastatin (urinary trypsin inhibitor; UTI) administration during the mid-trimester in women with singleton pregnancy and both cervical shortening and lower genital infections.

METHODS

Pregnant women with a short cervical length < 25 mm between 16 and 26 weeks of gestation and who had been diagnosed with a lower genital infection were randomly assigned for intravaginal UTI administration or placebo. All of the women were screened for infection or inflammation of the lower genital tract, and women with negative results were excluded.

RESULTS

Of the 92 patients with a short cervical length who were assessed for eligibility for this study, 86 singleton patients were enrolled. All patients were randomized to one of two treatment groups: patients administered UTI (n = 35) and placebo (n = 35). There were no differences between the two groups in the incidence of preterm delivery before 28, 30, 32, 34 and 37 weeks of gestation and in perinatal outcomes.

CONCLUSION

For women diagnosed with a short cervical length < 25 mm) between 16 and 26 weeks of gestation and lower genital infection, who were at risk of preterm birth, administration of transvaginal UTI with vaginal irrigation showed no apparent benefit. Future research on the efficacy of UTI should evaluate modified modes of UTI application.

A soft cervix, categorized by shear-wave elastography, in women with short or with normal cervical length at 18-24 weeks is associated with a higher prevalence of spontaneous preterm delivery

OBJECTIVE

To determine whether a soft cervix identified by shear-wave elastography between 18 and 24 weeks of gestation is associated with increased frequency of spontaneous preterm delivery (sPTD).

MATERIALS AND METHODS

This prospective cohort study included 628 consecutive women with a singleton pregnancy. Cervical length (mm) and softness [shear-wave speed: (SWS) meters per second (m/s)] of the internal cervical os were measured at 18-24 weeks of gestation. Frequency of sPTD <37 (sPTD<37) and <34 (sPTD<34) weeks of gestation was compared among women with and without a short (≤25 mm) and/or a soft cervix (SWS <25th percentile).

RESULTS

There were 31/628 (4.9%) sPTD<37 and 12/628 (1.9%) sPTD<34 deliveries. The combination of a soft and a short cervix increased the risk of sPTD<37 by 18-fold [relative risk (RR) 18.0 (95% confidence interval [CI], 7.7-43.9); P<0.0001] and the risk of sPTD<34 by 120-fold [RR 120.0 (95% CI 12.3-1009.9); P<0.0001] compared to women with normal cervical length. A soft-only cervix increased the risk of sPTD<37 by 4.5-fold [RR 4.5 (95% CI 2.1-9.8); P=0.0002] and of sPTD<34 by 21-fold [RR 21.0 (95% CI 2.6-169.3); P=0.0003] compared to a non-soft cervix.

CONCLUSIONS

A soft cervix at 18-24 weeks of gestation increases the risk of sPTD <37 and <34 weeks of gestation independently of cervical length.

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.

Screening for spontaneous preterm birth and resultant therapies to reduce neonatal morbidity and mortality: A review

Despite considerable effort aimed at decreasing the incidence of spontaneous preterm birth, it remains the leading cause of perinatal morbidity and mortality. Screening strategies are imperfect. Approaches used to identify women considered by historical factors to be low risk for preterm delivery (generally considered to be women with singleton pregnancies without a history of a previous preterm birth) as well as those at high risk for preterm birth (those with a previous preterm birth, short cervix, or multiple gestation) continue to evolve. Herein, we review the current evidence and approaches to screening women for preterm birth, and examine future directions for clinical practice. Further research is necessary to better identify at-risk women and provide evidence-based management.

Routine second trimester cervical length screening in low risk women identified women at risk of a 'very' preterm birth but did not reduce the preterm birth rate: a randomised study from India

Women (n = 300) at 'low risk' for a preterm birth (PTB), a singleton pregnancy and for a 16-24 week period of gestation (POG) were randomised to undergo cervical length (CL) measurement by transvaginal sonography (TVS) or not. The aim was to see if routine CL measurement and treatment of a short CL reduced the PTB rate. 'Low risk' was defined by an absence of a prior abortion or PTB of a singleton infant (>16 to <37 weeks) due to a spontaneous preterm labour (PTL) or a preterm pre-labour rupture of membranes (pPROM). The PTB rate was similar in the screened and unscreened group (10.3 and 8%, respectively, p = .433). In the screened group, women who delivered at 'term' or 'moderate to late' preterm (32 to <37 weeks) had a significantly higher mean CL (3.46 ± 0.41 and 3.48 ± 0.65 cm, respectively) than the women who delivered 'very' preterm (28 to 31 + 6 weeks; 2.05 ± 0.5 cm; p = .01). A short CL ≤2.5 cm was observed in two primigravidas (2/147 or 1.3%). They delivered at 28 + 3 and 30 + 6 weeks POG, respectively, despite treatment with vaginal progesterone and rescue cerclage in one. Their neonates were discharged in a good condition. In our low risk cohort, a routine second trimester CL measurement did not reduce the overall PTB rate. However, it identified two primigravidas at risk of having a 'very' PTB.Clinical Trials Registry (CTRI), India: Registration number CTRI/2016/01/010438 Impact statement What is already known on this subject? In women with a singleton pregnancy who are at a 'low risk' for preterm birth (PTB), a short cervical length (CL) at mid trimester measured by transvaginal sonography (TVS) identifies those at risk for a PTB. This risk may be reduced by the treatment with vaginal progesterone. At present, though evidence in favour of CL measurement in low-risk women exists, it is not established as a part of antenatal care. What do the results of this study add? A routine second trimester CL measurement in low risk women did not reduce the PTB rate. However, screening for a short CL helped to identify two primigravidas at risk for a 'very' PTB. It may be possible that detection and treatment of a short CL averted an 'extremely' PTB (<28 weeks) in these two women. What are the implications of these findings for clinical practice and/or further research? Future studies should assess the outcome of women with a short mid-trimester CL to see whether its treatment resulted in pregnancy prolongation and an improved neonatal outcome.

Is Midtrimester Cervical Length Associated with Preterm Birth in Women Evaluated for Preterm Labor?

OBJECTIVE

 This article aims to evaluate whether midtrimester cervical length (CL) is associated with improved prediction of preterm delivery in women presenting with preterm labor.

STUDY DESIGN

 This is a retrospective cohort study of women with a singleton gestation who underwent routine CL screening between 18 and 24 weeks of gestation between 2010 and 2014 who were later evaluated for preterm labor. Women were stratified by midtrimester CL quartile. Bivariable and multivariable analyses were performed to identify factors independently associated with preterm birth <37 weeks, <34 weeks, and delivery within 7 days of evaluation. Receiver operating characteristic (ROC) curves were created for multivariable equations with and without CL quartile to determine whether addition of CL improved the predictive capacity of the model for predicting preterm birth.

RESULTS

 A total of 460 women were evaluated for preterm labor and had midtrimester CL measurements available. When CL quartile was incorporated into a regression model including demographic and clinical characteristics associated with preterm birth, the area under the ROC curve was not improved (0.775 vs. 0.786, p = 0.20).

CONCLUSION

 While a shorter midtrimester CL quartile is associated with an increased incidence of preterm delivery in women evaluated for preterm labor, the addition of this variable to an existing model does not improve prediction of preterm birth.

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.