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

Screening for women at risk of spontaneous preterm birth, including cervical incompetence

Preterm births remain one of the biggest challenges in obstetrics worldwide. With the advancement of neonatal care, more premature neonates survive with long term consequences. Therefore, preventing or delaying preterm births starting from the preconceptional or antenatal periods are important. Among the numerous screening strategies described, not one can fit into all. Nonetheless, approaches including identifying women with modifiable risk factors for preterm births, genitourinary infections and short cervical length are the most useful. In this article, the current evidence is summarized and the best strategies for common clinical scenerios including cervical incompetence, history of second trimester loss or early preterm births, incidental short cervix and multiple pregnancy are discussed.

Perinatal and neonatal outcomes of high-risk asymptomatic women from a specialist preterm birth surveillance clinic

OBJECTIVES

To report the perinatal outcomes of high-risk asymptomatic women who attended a specialist preterm surveillance clinic (PSC) to undergo screening for spontaneous preterm birth (PTB) in Ireland.

METHODS

Single center, retrospective cohort study of asymptomatic high risk women who attended the PSC between January 2019 and December 2022. A comprehensive database of all patients who attended the clinic during the study period was constructed and analyzed. Overall outcomes were reported, and stratified per the occurrence of preterm or term birth. Iatrogenic PTBs were included in the outcome data.

RESULTS

Following exclusions for loss-to-follow-up, 762 cases were analyzed, constituting 2262 PSC visits. Of those, 183 women were prescribed progesterone (24.0 %), and 100 women underwent cervical cerclage (13.1 %) to prevent spontaneous PTB. Overall, 2.4 %, 6.2 % and 18.6 % of participants gave birth prior to 30 weeks, 34 weeks, and 37 weeks, respectively. The median gestational age at birth for the entire cohort was 38.6 weeks (inter-quartile range (IQR) 37.2-39.6 weeks). Women who delivered < 37 weeks were significantly more likely to be smokers (p = 0.030), have a previous spontaneous PTB (p = 0.016), have multiple pregnancies (p < 0.001), type 1 or 2 diabetes (p = 0.044), or have a previous full dilatation caesarean section birth (p = 0.024). Infants born prior to 37 weeks were more likely to have a lower median birthweight (2270 vs 3300 g, p < 0.001), be admitted to a neonatal intensive care unit (53.8 % vs 2.3 %, p < 0.001) or experience short-term morbidity, including respiratory support (38.0 % vs 1.6 %, p < 0.001).

CONCLUSIONS

Over 80% of women deemed to be at high risk of PTB gave birth at term gestations following attendance at a PSC during pregnancy. Most women can be successfully managed without interventions, instead employing a policy of serial cervical surveillance, to identify those at greatest risk of PTB.

Preterm Birth: Screening and Prediction

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

Predicting spontaneous preterm birth in asymptomatic high-risk women with cervical cerclage

OBJECTIVE

To determine the performance of the predictive markers of spontaneous preterm birth, cervicovaginal quantitative fetal fibronectin (fFN) and cervical length, in asymptomatic high-risk women with transabdominal, history-indicated or ultrasound-indicated cervical cerclage.

METHODS

This was a secondary analysis of a prospective cohort of asymptomatic high-risk women with cervical cerclage and no other prophylactic intervention (including progesterone), who attended the preterm birth clinic at a central London teaching hospital between October 2010 and September 2016. Women had either transabdominal cerclage, placed prior to conception, history-indicated cerclage, placed before 14 weeks' gestation, or ultrasound-indicated cerclage for a short cervix (< 25 mm), placed before 24 weeks. All women underwent serial cervical length assessment on transvaginal ultrasound in the second trimester (16-28 weeks), and quantitative fFN testing from 18 weeks onward. Test performance was analyzed for the prediction of spontaneous preterm birth before 30 weeks (cerclage failure), 34 weeks and 37 weeks, using receiver-operating-characteristics (ROC)-curve analysis.

RESULTS

Overall, 181 women were included in the analysis. Cervical length and fFN were strong predictors of spontaneous preterm birth before 30 weeks in women with cerclage, with areas under the ROC curve (AUC) of 0.86 (95% CI, 0.79-0.94) and 0.84 (95% CI, 0.75-0.92), respectively. Cervical length was a better predictor of preterm birth before 30 weeks in women with history-indicated compared to those with ultrasound-indicated cerclage, although both showed clinical utility (AUC, 0.96 (95% CI, 0.91-1.00) vs 0.79 (95% CI, 0.66-0.91); P = 0.01). Quantitative fFN was a strong predictor of spontaneous preterm birth before 30 weeks in women with history-indicated cerclage (AUC, 0.91 (95% CI, 0.75-1.00)) and retained clinical utility in those with ultrasound-indicated cerclage (AUC, 0.76 (95% CI, 0.64-0.89)). There were no spontaneous deliveries before 34 weeks in women with a transabdominal cerclage, so AUC was not calculated. Delivery was delayed significantly in this group (P < 0.01).

CONCLUSIONS

Cervical length and quantitative fFN retain clinical utility for the prediction of spontaneous preterm birth in women with cervical cerclage, and prediction is best in women with a history-indicated stitch. These tests can be relied upon to discriminate risk and have utility when planning clinical management with regard to treatment failure. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

A prospective, double-blinded cohort study using quantitative fetal fibronectin testing in symptomatic women for the prediction of spontaneous preterm delivery

BACKGROUND

Spontaneous preterm birth (PTB) affects 6.5% of deliveries in Hong Kong. Quantitative fetal fibronectin (fFN) is under-utilised as a test for PTB prediction in Hong Kong. Our objective was to evaluate the effectiveness of quantitative fFN in predicting spontaneous PTB in women with symptoms of threatened preterm labour (TPTL) in our population.

METHODS

A prospective, double-blinded cohort study of women with a singleton gestation and TPTL symptoms presenting to a tertiary hospital in Hong Kong between 24 + 0 to 33 + 6 weeks was performed from 1st October 2020 and 31st October 2021. Women with vaginal bleeding, ruptured membranes, and cervical dilation > 3 cm were excluded. The primary outcome was to test the characteristics of quantitative fFN in predicting spontaneous PTB < 37 weeks. Secondary outcome was to investigate the relationship between fFN value and time to PTB. Test characteristics of quantitative fFN at different thresholds were evaluated.

RESULTS

48 women with TPTL were recruited. All had fFN testing at admission with the results being concealed from the obstetrician managing the patient. 10 mothers had PTB (< 37 weeks' gestation). 7/48 (15%) had a subsequent PTB within 14 days from testing and 5 (10%) delivered within 48 h. The negative predictive value (NPV) of predicting delivery within 14 days was 97.3% and 100% when using a cut-off of < 50ng/ml and < 10ng/ml respectively. Using > 200 ng/ml as cut-off can also reliably predict delivery within 48 h - 7 days with positive predictive value PPV of 100%; as well as PTB before 37 weeks.

CONCLUSIONS

Quantitative fFN has predictive value for spontaneous PTB prediction in symptomatic women in a Hong Kong population. fFN concentration could help clinicians rule out PTB and avoid unnecessary interventions and hospitalisation.

How can obstetricians improve outcomes for infants born extremely preterm?

Prematurity remains a leading cause of perinatal morbidity and mortality, and also has significant implications for long-term health. Obstetricians have a key role to play in improving outcomes for infants born at extremely preterm gestations. This review explores the evidence for interventions available to obstetricians caring for women at risk of birthing at extremely preterm gestations, including antenatal corticosteroids, magnesium sulfate, tocolysis and antibiotics. It also addresses the importance of strategies to facilitate safe in-utero transfer, to maximise the chance of extremely preterm births occurring in tertiary centers, and the clinical value of strategies by which preterm birth can be predicted. The paper concludes with an appraisal of evidence for different modes of birth at extremely preterm gestations, and for delayed cord clamping.

Impact of past obstetric history and cervical excision on preterm birth rate

INTRODUCTION

To determine the impact on preterm birth (PTB) of a history of large loop excision of the transformation zone (LLETZ)-alone compared with a history of previous preterm birth-alone (PPTB) or a history of both (LLETZ+PPTB). Secondary analyses were performed to evaluate the impact of antenatal interventions, depth of cervical excision, and patient risk factors on PTB rate in each cohort.

MATERIAL AND METHODS

A retrospective observational cohort study of women referred to a tertiary Antenatal Prematurity Prevention Clinic with a history of LLETZ, PPTB, or LLETZ+PPTB. Information was collated from routinely collected clinical data on patient demographics, previous obstetric history, LLETZ dimensions, antenatal investigations/interventions, and gestation at delivery.

RESULTS

A total of 1231 women with singleton pregnancies were included, 543 with history of LLETZ-alone, 607 with a history of PPTB-alone and 81 with a history of LLETZ+PPTB. PTB rates were 8.8% in the LLETZ-alone group, which mirrored the PTB rate in the local background obstetric population (8.9%) compared with 28.7% in the PPTB-alone and 37.0% in the LLETZ+PPTB cohorts. PTB rates were higher in LLETZ cohorts treated with antenatal intervention (cervical cerclage or progesterone pessary) and there was no evidence of an effect of intervention on risk of PTB in post-excision patients with identified shortened mid-trimester cervical length. Logistic regression modeling identified PPTB as a strong predictor of recurrent PTB. Excision depth was correlated with gestation at delivery in the LLETZ-alone group (r = -0.183, p < 0.01) although this only reached statistical significance at depths of 20 mm or more (odds ratio [OR] 3.40, 95% CI 1.04-1.11, p = 0.04). Depth of excision was not correlated with delivery gestation in the LLETZ+PPTB group (r = -0.031, p = 0.82).

CONCLUSIONS

PPTB has a greater impact on subsequent PTB risk compared with depth of cervical excisional treatment. The value and nature of antenatal interventions should be investigated in the post-excision population.

Midwifery continuity of care versus standard maternity care for women at increased risk of preterm birth: A hybrid implementation-effectiveness, randomised controlled pilot trial in the UK

BACKGROUND

Midwifery continuity of care is the only health system intervention shown to reduce preterm birth (PTB) and improve perinatal survival, but no trial evidence exists for women with identified risk factors for PTB. We aimed to assess feasibility, fidelity, and clinical outcomes of a model of midwifery continuity of care linked with a specialist obstetric clinic for women considered at increased risk for PTB.

METHODS AND FINDINGS

We conducted a hybrid implementation-effectiveness, randomised, controlled, unblinded, parallel-group pilot trial at an inner-city maternity service in London (UK), in which pregnant women identified at increased risk of PTB were randomly assigned (1:1) to either midwifery continuity of antenatal, intrapartum, and postnatal care (Pilot study Of midwifery Practice in Preterm birth Including women's Experiences [POPPIE] group) or standard care group (maternity care by different midwives working in designated clinical areas). Pregnant women attending for antenatal care at less than 24 weeks' gestation were eligible if they fulfilled one or more of the following criteria: previous cervical surgery, cerclage, premature rupture of membranes, PTB, or late miscarriage; previous short cervix or short cervix this pregnancy; or uterine abnormality and/or current smoker of tobacco. Feasibility outcomes included eligibility, recruitment and attrition rates, and fidelity of the model. The primary outcome was a composite of appropriate and timely interventions for the prevention and/or management of preterm labour and birth. We analysed by intention to treat. Between 9 May 2017 and 30 September 2018, 334 women were recruited; 169 women were allocated to the POPPIE group and 165 to the standard group. Mean maternal age was 31 years; 32% of the women were from Black, Asian, and ethnic minority groups; 70% were in employment; and 46% had a university degree. Nearly 70% of women lived in areas of social deprivation. More than a quarter of women had at least one pre-existing medical condition and multiple risk factors for PTB. More than 75% of antenatal and postnatal visits were provided by a named/partner midwife, and a midwife from the POPPIE team was present at 80% of births. The incidence of the primary composite outcome showed no statistically significant difference between groups (POPPIE group 83.3% versus standard group 84.7%; risk ratio 0.98 [95% confidence interval (CI) 0.90 to 1.08]; p = 0.742). Infants in the POPPIE group were significantly more likely to have skin-to-skin contact after birth, to have it for a longer time, and to breastfeed immediately after birth and at hospital discharge. There were no differences in other secondary outcomes. The number of serious adverse events was similar in both groups and unrelated to the intervention (POPPIE group 6 versus standard group 5). Limitations of this study included the limited power and the nonmasking of group allocation; however, study assignment was masked to the statistician and researchers who analysed the data.

CONCLUSIONS

In this study, we found that it is feasible to set up and achieve fidelity of a model of midwifery continuity of care linked with specialist obstetric care for women at increased risk of PTB in an inner-city maternity service in London (UK), but there is no impact on most outcomes for this population group. Larger appropriately powered trials are needed, including in other settings, to evaluate the impact of relational continuity and hypothesised mechanisms of effect based on increased trust and engagement, improved care coordination, and earlier referral on disadvantaged communities, including women with complex social factors and social vulnerability.

TRIAL REGISTRATION

We prospectively registered the pilot trial on the UK Clinical Research Network Portfolio Database (ID number: 31951, 24 April 2017). We registered the trial on the International Standard Randomised Controlled Trial Number (ISRCTN) (Number: 37733900, 21 August 2017) and before trial recruitment was completed (30 September 2018) when informed that prospective registration for a pilot trial was also required in a primary clinical trial registry recognised by WHO and the International Committee of Medical Journal Editors (ICMJE). The protocol as registered and published has remained unchanged, and the analysis conforms to the original plan.

The experience and outcomes of a specialised preterm birth clinic in New Zealand

BACKGROUND

A greater understanding of the risk factors for spontaneous preterm birth and the importance of risk stratification to guide interventions has led to the introduction of preterm birth prevention clinics.

AIM

To evaluate the experience and outcomes of the first specialised preterm birth clinic in New Zealand.

MATERIALS AND METHODS

This observational study reviewed pregnancies cared for in a preterm birth clinic from 2013 to 2018. Cases were identified and data collected from a maternity database and electronic medical records. Analysis was by referral type.

RESULTS

A total of 423 cases were included; 309 elective and 22 acute referrals in pregnancy, and 92 consultations outside pregnancy. For those referred electively in pregnancy, 138/309 (44.7%) fulfilled multiple referral criteria, and 57/309 (18.4%) had ≥2 previous spontaneous preterm births or second trimester losses. Excluding five pregnancies with first trimester miscarriage, 77/304 (25.3%) were managed with a history-indicated cerclage (11 placed pre-conception) and 217/304 (71.4%) had cervical surveillance as primary management, of which 133 (61.3%) did not require treatment. The remaining had treatment for a short cervix; 37 (17.0%) received an ultrasound-indicated cerclage only, 21 (9.7%) vaginal progesterone only and 26 (12.0%) both. Five women (1.6%) had a second trimester loss at 13⁺⁰ -19⁺⁶ and 58/297 (19.5%) had a spontaneous preterm birth at 20⁺⁰ -36⁺⁶  weeks. The 'take home baby' rate was 95.4%.

CONCLUSIONS

Pregnancy outcomes were similar to those reported by other preterm birth prevention clinics. The majority of women who received cervical surveillance as primary management were able to avoid additional treatment.

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

Background

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

Methods

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

Results

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

Conclusions

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

Trial registration

Systematic review registration number: CRD42019131470.

Cervical length and quantitative fetal fibronectin in the prediction of spontaneous preterm birth in asymptomatic women with congenital uterine anomaly

BACKGROUND

Congenital uterine anomalies are associated with late miscarriage and spontaneous preterm birth.

OBJECTIVE

Our aim was 1) to determine the rate of spontaneous preterm birth in each type of congenital uterine anomaly, and 2) to assess the performance of quantitative fetal fibronectin and cervical length measurement by transvaginal ultrasound in asymptomatic women with congenital uterine anomalies for the prediction of spontaneous preterm birth at <34 and <37 weeks of gestation.

MATERIALS AND METHODS

This was a retrospective cohort of women with congenital uterine anomalies asymptomatic for spontaneous preterm birth, from 4 tertiary referral centers in the United Kingdom (2001-2016). Congenital uterine anomalies were categorized into fusion (unicornuate, didelphic, and bicornuate uteri) or resorption defects (septate, with or without resection, and arcuate uteri), based on prepregnancy diagnosis. All women underwent serial transvaginal ultrasound cervical length assessment in the second trimester (16 to 24 weeks' gestation); a subgroup underwent quantitative fetal fibronectin testing from 18 weeks' gestation. We investigated the relationship between congenital uterine anomalies and predictive test performance for spontaneous preterm birth at <34 and <37 weeks' gestation.

RESULTS

A total of 319 women were identified as having congenital uterine anomalies in our high-risk population. Of the women, 7% (23/319) delivered spontaneously at <34 weeks' gestation and 18% (56/319) at <37 weeks' gestation. Rates of spontaneous preterm birth by type were as follows: 26% (7/27) for unicornuate, 21% (7/34) for didelphic, 16% (31/189) for bicornuate, 13% (7/56) for septate, and 31% (4/13) for arcuate. In all, 80% (45/56) of women who had spontaneous preterm birth at <37 weeks did not develop a short cervical length (<25 mm) during the surveillance period (16-24 weeks). The diagnostic accuracy of short cervical length had a low sensitivity (20.3) for predicting spontaneous preterm birth at <34 weeks. Cervical length had an area under the receiver operating curve of 0.56 (95% confidence interval, 0.48-0.64) and 0.59 (95% confidence interval, 0.55-0.64) for prediction of spontaneous preterm birth at <34 and <37 weeks, respectively. The area under the curve for cervical length to predict spontaneous preterm birth at <34 weeks was 0.48 for fusion defects (95% confidence interval, 0.39-0.57) but 0.78 (95% confidence interval, 0.66-0.91) for women with resorption defects. Overall quantitative fetal fibronectin had an area under the curve of 0.63 (95% confidence interval, 0.49-0.77) and 0.58 (95% confidence interval, 0.49- 0.68) for prediction of spontaneous preterm birth at <34 and <37 weeks, respectively. The area under the curve for prediction of spontaneous preterm birth at <37 weeks with quantitative fetal fibronectin for fusion defects was 0.52 (95% confidence interval, 0.41-0.63) but 0.79 (95% confidence interval, 0.63-0.95) for women with resorption defects. Results were similar when women with intervention were excluded.

CONCLUSION

The commonly used markers cervical length and quantitative fetal fibronectin have utility in prediction of spontaneous preterm birth in resorption congenital uterine defects but not in fusion defects. This is contrary to findings in other high-risk populations. These findings need to be accounted for when planning antenatal care, and have potential implications for predictive tests used in spontaneous preterm birth surveillance and intervention.

Predictive value of the quantitative fetal fibronectin levels for the management of women presenting with threatened preterm labour - A revised cut off level: A retrospective cohort study

Objective

To evaluate a new a cut off level of fetal fibronectin as a predictor of birth in women with threatened preterm labour.

Design

A retrospective cohort study performed at Ipswich hospital, Ipswich, Queensland, Australia, in women with threatened preterm labour with intact membranes between 23 weeks to 34 + 6 week gestation.

Study design

A quantitative fetal fibronectin (fFN) was performed. Maternal demographics and birth outcome data were extracted from the routinely collected perinatal data held by the hospital. The odds of preterm birth were estimated for each cut off value of fFN (10, 50 and 200 ng ml⁻¹) using logistic regression and accounting for multiple presentations by the same woman.

Results

Among the 447 presentations and 376 pregnancies, rates of preterm birth <34 weeks were 2.9%, 9.2%, 3.3%, 19.6%, 4.2% and 35.3% for each category of values respectively (fFN <10, ≥10, <50, ≥50, <200 and ≥200 ng ml⁻¹). Birth rates within 7 d of testing were 1.1%, 7.5%, 1.8%, 16.1%, 2.1% and 41.2% respectively. Comparing fFN level of <10 to a level of 10-199 ng ml⁻¹ there was no significant increase in odds of preterm birth < 34 weeks or birth within the next 7 d (OR 2.28, 95% CI 0.84-6.17 and OR 3.61, 95% CI 0.89-14.7 respectively.

Conclusion

In women presenting with TPL, those with levels of <200 ng ml⁻¹ have a low risk of birthing within 7 d or before 34 weeks gestation. This allows a personalised decision making and probable discharge home without need for steroid loading.

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

Background

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

Methods

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

Discussion

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

Trial registration

ISRCTN37733900. Retrospectively registered on 21 August 2017.

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

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

Evaluation of fetal fibronectin for threatened preterm labour in reducing inappropriate interventions

BACKGROUND

Preterm birth is associated with significant perinatal morbidity and mortality. The fetal fibronectin test (fFN) is used to manage women presenting with threatened preterm labour (TPTL).

AIM

To evaluate the use of fFN in women presenting with TPTL with regard to hospital admission, tertiary hospital transfer and use of tocolytics and steroids in our hospital, against recommended guidelines. The ability of fFN <10 ng/mL, 10-49 ng/mL, 50-199 ng/mL and >200 ng/mL to predict outcome was also examined.

MATERIAL AND METHODS

This was a single-centre retrospective study from January 2015 to June 2017. All women who presented to Ipswich hospital, a level two facility for births at >32 weeks of gestation, between 23 and 34⁶  weeks of gestation with TPTL and who had fFN tests were included in the study.

RESULTS

Fetal fibronectin <50 ng/mL had a negative predictive value of 93.5% (95% CI 86.5-97.1). Despite this assurance, one in four presentations resulted in hospital admission and nearly one in ten in steroids and tocolysis administration. Birth <34 weeks was 0% for fFN <10 and 2% for women with fFN levels <200 ng/mL compared to nearly 30% for levels >200 ng/mL.

CONCLUSION

There is noncompliance with use of fFN to its full potential. This small study also provides support for the use of a 200 ng/mL cut-off fFN level for birth <34 weeks. This would avoid the need to transfer to a tertiary facility many women who present with TPTL.

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

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

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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