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

A proposed method to predict preterm birth using clinical data, standard maternal serum screening, and cholesterol

OBJECTIVE

The objective of the study was to create a predictive model for preterm birth (PTB) from available clinical data and serum analytes.

STUDY DESIGN

Serum analytes and routine pregnancy screening plus cholesterol and corresponding health information were linked to birth certificate data for a cohort of 2699 Iowa women with serum sampled in the first and second trimester. Stepwise logistic regression was used to select the best predictive model for PTB.

RESULTS

Serum screening markers remained significant predictors of PTB, even after controlling for maternal characteristics. The best predictive model included maternal characteristics, first-trimester total cholesterol, total cholesterol change between trimesters, and second-trimester alpha-fetoprotein and inhibin A. The model showed better discriminatory ability than PTB history alone and performed similarly in subgroups of women without past PTB.

CONCLUSION

Using clinical and serum screening data, a potentially useful predictor of PTB was constructed. Validation and replication in other populations, and incorporation of other measures that identify PTB risk, like cervical length, can be a step toward identifying additional women who may benefit from new or currently available interventions.

The negative predictive value of cervical interleukin-6 for the risk assessment of preterm birth

OBJECTIVE

To determine the potential clinical use of cervical interleukin-6 (IL-6) as a negative predictor of preterm birth in symptomatic women.

STUDY DESIGN

Observational prospective study carried out in a tertiary hospital.

PATIENTS AND METHODS

We studied 100 singleton pregnant women with threatened preterm delivery and intact membranes, between 24 and 34 weeks, recruited during the period 2006-2008. A cervical swab for IL-6 detection was taken and a transvaginal ultrasound scan was performed for measuring the cervical length.

RESULTS

Five women delivered within 2 d and six women within 7 d. A high cervical IL-6 concentration was found in these women. The area under the ROC curve for cervical IL-6 was 0.97 for deliveries within 2 d after the test, and 0.85 for deliveries within 7 d. The optimal cut-off point was a cervical IL-6 concentration of 210 pg/ml. The negative predictive value (NPV) was 100% for deliveries within 2 d, and 98.5% for deliveries within 7 d (when considering a prevalence of preterm birth of 8%). Cervical IL-6 and sonographic measurement of cervical length showed similar NPV.

CONCLUSION

A low-cervical IL-6 concentration can accurately identify symptomatic women with a very low chance to progress to preterm birth within 2-7 d.

Affordability of programmes to prevent spontaneous preterm birth in Austria: a budget impact analysis

BACKGROUND

Preterm birth is a rising health problem in Europe generally, and in Austria specifically. Decision makers require objective information on the effects and costs of measures to prevent preterm birth.

METHODS

We undertook a budget impact analysis from a public payer perspective and for a 1-year and 5-year time horizon for five prevention approaches to reduce preterm birth. These were cervix screening + progesterone application, progesterone injection, smoking cessation, fish oil supplementation and infection screening. We analysed affordability in terms of programme costs and potential cost savings.

RESULTS

Programme costs range from below €50 000 (cervix screening in high-risk pregnancy) to €500 000 (universal infection screening). The lowest health effects have been shown for smoking cessation programmes (-10 preterm births per year), whereas infection screening demonstrated the largest effect (-230 preterm births per year). In the base-case analysis, all programmes are potentially cost saving (-€500 000 to -€13 million per year). In the sensitivity analyses, preterm birth costs, target group size and (partly) unit costs of programme components have an influence on potential cost savings. However, except for two programmes, the results are robust concerning an overall economic net benefit of the programmes analysed compared with no programme. The study is mainly limited by the quality of some cost data and choice of the reference scenario.

CONCLUSION

When considering potential cost savings, the five prevention programmes analysed seem affordable, with cervix screening and infection screening likely being the most promising in Austria.

The obstetric syndromes: clinical relevance of placental hormones

Preterm delivery, preeclampsia and intrauterine growth restriction are the major diseases of pregnancy. A key role in their pathogenesis is played by the placenta, which is the source of hormones and other important regulatory molecules providing the metabolic and endocrine homeostasis of the fetal-placental unit. Since obstetric syndromes are characterized by important maternal and neonatal morbidity and mortality worldwide, numerous efforts have been made over the years to prevent and treat them. Due to their complex pathogenesis, however, the therapy is poor and not very effective. Therefore, great emphasis is currently given to the prevention of these diseases through the identification of biochemical and biophysical markers, among which placental factors play a crucial role. The increasing knowledge of the role of placental molecules can indeed lead to the development of new therapeutic and diagnostic tools.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Short cervix syndrome: current knowledge from etiology to the control

BACKGROUND

Preterm delivery is one of the most serious public health problems and is the most important factor relating to neonatal morbidity and mortality. The strategies for preventing it include understanding the risk factors, with specific interventions. Recently, uterine cervix measurements using ultrasonography and vaginal administration of progesterone have gained importance in predicting and secondarily preventing spontaneous preterm delivery.

OBJECTIVE

To describe the short cervix syndrome, including its etiology, diagnosis, and possible therapies.

METHODS

Research in ISI, Pubmed, and Scielo database using the words short cervix, preterm delivery, sludge, cervical funneling, cervical gland area, progesterone, cerclage, and pessary.

RESULTS

We found a lot of articles about this topic, including randomized controlled trials. The etiology is multifactorial, being the diagnosis based in a cervix shortening at 20-24 weeks. The history and measurement of cervix length by transvaginal ultrasound have been shown to be effective to select the high risk pregnancies. The progesterone, cervical cerclage, and cervical pessary showed to be effective to reduce the preterm delivery in pregnant women with short cervix.

CONCLUSION

The successful management of pregnant women presenting a short cervix depends on the understanding that cervical shortening is the final common path for several causes of preterm delivery. The best approach should be individualized to each patient.

Effectiveness of interventions for the prevention of small-for-gestational age fetuses and perinatal mortality: a review of systematic reviews

Previous narrative reviews in this area have concluded that there are few interventions that are likely to be beneficial and that further high-quality research is required. Our objective was to perform a review of systematic reviews of the effectiveness of interventions for the prevention of small-for-gestational age (SGA) fetuses and perinatal mortality, to summarize the most up-to-date evidence and assess quality. Searches were carried out by using Medline, Embase, Cochrane Library and DARE (inception to September 2011), by hand searching of journal and reference lists and by contact with experts. Systematic reviews of randomized controlled trials were selected. Two reviewers independently selected articles and assessed the methodological and reporting quality. Data were extracted on study characteristics, quality and results. Summary data were presented as relative risks (RRs) and 95% confidence intervals (CIs). There were 834 randomized controlled trials (>668 672 participants), reporting on 45 different interventions. The most effective interventions to prevent the SGA fetus were antiplatelets at <16 weeks in women at risk of pre-eclampsia (RR 0.47; CI 0.30-0.74) and progesterone therapy for prevention of preterm birth (RR 0.64; CI 0.49-0.83). For the prevention of perinatal mortality in high-risk women, antiplatelets (RR 0.69; CI 0.53-0.90) and antenatal corticosteroids (RR 0.77; CI 0.67-0.89) were effective interventions. It is concluded that effective interventions are available for reducing the occurrence of SGA fetuses and preventing related perinatal mortality. Some are effective in all women, while others target specific co-morbidities. There is a need to consider a comprehensive approach to primary prevention that targets SGA along with pre-eclampsia and preterm birth.

Trial protocol OPPTIMUM-- does progesterone prophylaxis for the prevention of preterm labour improve outcome?

BACKGROUND

Preterm birth is a global problem, with a prevalence of 8 to 12% depending on location. Several large trials and systematic reviews have shown progestogens to be effective in preventing or delaying preterm birth in selected high risk women with a singleton pregnancy (including those with a short cervix or previous preterm birth). Although an improvement in short term neonatal outcomes has been shown in some trials these have not consistently been confirmed in meta-analyses. Additionally data on longer term outcomes is limited to a single trial where no difference in outcomes was demonstrated at four years of age of the child, despite those in the "progesterone" group having a lower incidence of preterm birth.

METHODS/DESIGN

The OPPTIMUM study is a double blind randomized placebo controlled trial to determine whether progesterone prophylaxis to prevent preterm birth has long term neonatal or infant benefit. Specifically it will study whether, in women with singleton pregnancy and at high risk of preterm labour, prophylactic vaginal natural progesterone, 200 mg daily from 22 - 34 weeks gestation, compared to placebo, improves obstetric outcome by lengthening pregnancy thus reducing the incidence of preterm delivery (before 34 weeks), improves neonatal outcome by reducing a composite of death and major morbidity, and leads to improved childhood cognitive and neurosensory outcomes at two years of age. Recruitment began in 2009 and is scheduled to close in Spring 2013. As of May 2012, over 800 women had been randomized in 60 sites.

DISCUSSION

OPPTIMUM will provide further evidence on the effectiveness of vaginal progesterone for prevention of preterm birth and improvement of neonatal outcomes in selected groups of women with singleton pregnancy at high risk of preterm birth. Additionally it will determine whether any reduction in the incidence of preterm birth is accompanied by improved childhood outcome.

TRIAL REGISTRATION

ISRCTN14568373.

Changes in the Th1:Th2 cytokine bias in pregnancy and the effects of the anti-inflammatory cyclopentenone prostaglandin 15-deoxy-Δ(12,14)-prostaglandin J2

Pregnancy is a complex immunological state in which a bias towards T helper 2 (Th2) protects the fetus. Evidence suggests that proinflammatory cytokines increase the risk of poor neonatal outcome, independently of the direct effect of preterm labour. The anti-inflammatory prostaglandin 15-deoxy-Δ^12,14-Prostaglandin J₂ (15dPGJ₂) inhibits nuclear factor Kappa B (NF-κB) in amniocytes and myocytes in vitro and is a ligand for the chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2) receptor. Here we examine the Th1:Th2 cytokine bias in pregnancy and whether 15dPGJ₂ could be used to inhibit the production of the proinflammatory cytokines through inhibition of NF-κB while simultaneously promoting Th2 interleukin 4 (IL-4) synthesis via CRTH2 in T helper cells. Peripheral blood mononuclear cells (PBMCs) from women at 28 weeks, term pre-labour, term labour as well as non-pregnant female controls were cultured with 15dPGJ₂ or vehicle control and stimulated with phorbol myristyl acetate (PMA)/ionomycin. The percentage of CD4⁺ cells producing interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) in response to PMA/ionomycin was significantly reduced in pregnancy. 15dPGJ₂ reduced IFN-γ and TNF-α production in stimulated T helper cells, but did not alter IL-4 production in CRTH2^+ve cells. 15dPGJ₂ also reduced phospho-p65 in stimulated PBMCs. In summary, 15dPGJ₂ suppresses the Th1 response of PBMCs during pregnancy and active labour whilst maintaining the Th2 response suggesting a therapeutic benefit in reducing neonatal morbidity in inflammation-induced PTL.

Value of serum urocortin concentration in the prediction of preterm birth

AIM

Preterm delivery is a serious problem during pregnancy with remarkable neonatal adverse effects. Prediction of preterm delivery in women with preterm uterine contractions or signs of preterm labor is critical because if these women are identified they can be referred to tertiary centers. The present study aimed to evaluate the value of maternal serum urocortin concentration for predicting preterm delivery in women with signs of spontaneous preterm labor.

MATERIAL AND METHODS

  A cohort study was conducted on pregnant women at a gestational age of 28-36 weeks who were admitted to the labor ward with spontaneous preterm labor. A blood sample was obtained from all participants to measure serum urocortin. The women were monitored up to delivery and serum urocortin was compared between women with preterm delivery and those who delivered at term (37 weeks of gestation). Receiver Operating Characteristic (ROC) curve analysis was used to determine sensitivity and specificity if applicable.

RESULTS

  One hundred and sixty pregnant women finished the study. One hundred and forty-eight (92.5%) of the women delivered preterm. Mean serum urocortin in the preterm delivery group was higher than in the term group, but without statistical significant difference (392.6 ± 29.23 vs 113.2 ± 11.0. pg/mL, respectively, P = 0.252). Area under the ROC curve was 0.6, which shows that this test is not appropriate for predicting preterm delivery in women with preterm labor.

CONCLUSION

  Serum urocortin could not predict women who delivered preterm among women with signs of preterm labor.

Home uterine monitoring for detecting preterm labour

BACKGROUND

To reduce the morbidity and mortality associated with preterm birth, home uterine activity monitoring aims for early detection of increased contraction frequency, and early intervention with tocolytic drugs to inhibit labour and prolong pregnancy. However, the effectiveness of such monitoring is disputed.

OBJECTIVES

To determine whether home uterine activity monitoring is effective in improving the outcomes for women and their infants considered to be at high risk of preterm birth, when compared with conventional or other care packages that do not include home uterine monitoring.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 November 2011), CENTRAL (The Cochrane Library 2011, Issue 4 of 4), MEDLINE (1966 to 30 November 2011), EMBASE (1974 to 30 November 2011), CINAHL (1982 to 30 November 2011) and scanned reference lists of retrieved studies.

SELECTION CRITERIA

Randomised control trials of home uterine activity monitoring, with or without patient education programmes, for women at risk for preterm birth, in comparison to the same care package without home uterine activity monitoring.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, extracted data and assessed risk of bias. Data were checked for accuracy. We did not attempt to contact authors to resolve queries.

MAIN RESULTS

There were 15 included studies (total number of enrolled participants 6008); 13 studies contributed data. Women using home uterine monitoring were less likely to experience preterm birth at less than 34 weeks (risk ratio (RR) 0.78; 95% confidence interval (CI) 0.62 to 0.99; three studies, n = 1596; fixed-effect analysis). However, this significant difference was not evident when we carried out a sensitivity analysis, restricting the analysis to studies at low risk of bias based on study quality (RR 0.75; 95% CI 0.57 to 1.00, one study, 1292 women). There was no significant difference in the rate of perinatal mortality (RR 1.22; 95% CI 0.86 to 1.72; two studies, n = 2589).There was no significant difference in the number of preterm births at less than 37 weeks (average RR 0.85; CI 0.72 to 1.01; eight studies, n = 4834; random effects, T(2) = 0.03, I(2) = 68%). Infants born to women using home uterine monitoring were less likely to be admitted to neonatal intensive care unit (average RR 0.77; 95% CI 0.62 to 0.96; five studies, n = 2367; random-effects, T(2) = 0.02, I(2) = 32%). Although this difference was not statistically significant when only high quality studies were included (RR 0.86; 95% CI 0.74 to 1.01; one study, n = 1292). Women using home uterine monitoring made more unscheduled antenatal visits (mean difference (MD) 0.49; 95% CI 0.39 to 0.62; two studies, n = 2807). Women using home uterine monitoring were also more likely to have prophylactic tocolytic drug therapy (average RR 1.21; 95% CI 1.01 to 1.45; seven studies, n = 4316; random-effects. T(2) = 0.03, I(2) = 62%) but this difference was no longer significant when the analysis was restricted to high quality studies (average RR 1.22; 95% CI 0.90 to 1.65, three studies, n = 3749,random effects, T(2) = 0.05, I(2) = 76%). One small study reported that the home uterine monitoring group spent fewer days in hospital antenatally. No data on maternal anxiety or acceptability were found.

AUTHORS' CONCLUSIONS

Home uterine monitoring may result in fewer admissions to a neonatal intensive care unit but more unscheduled antenatal visits and tocolytic treatment. There is no impact on maternal and perinatal outcomes such as perinatal mortality or incidence of preterm birth.

Cervical pessary in pregnant women with a short cervix (PECEP): an open-label randomised controlled trial

BACKGROUND

Most previous studies of the use of cervical pessaries were either retrospective or case controlled and their results showed that this intervention might be a preventive strategy for women at risk of preterm birth; no randomised controlled trials have been undertaken. We therefore undertook a randomised, controlled trial to investigate whether the insertion of a cervical pessary in women with a short cervix identified by use of routine transvaginal scanning at 20-23 weeks of gestation reduces the rate of early preterm delivery.

METHODS

The Pesario Cervical para Evitar Prematuridad (PECEP) trial was undertaken in five hospitals in Spain. Pregnant women (aged 18-43 years) with a cervical length of 25 mm or less were randomly assigned according to a computer-generated allocation sequence by use of central telephone in a 1:1 ratio to the cervical pessary or expectant management (without a cervical pessary) group. Because of the nature of the intervention, this study was not masked. The primary outcome was spontaneous delivery before 34 weeks of gestation. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00706264.

FINDINGS

385 pregnant women with a short cervix were assigned to the pessary (n=192) and expectant management groups (n=193), and 190 were analysed in each group. Spontaneous delivery before 34 weeks of gestation was significantly less frequent in the pessary group than in the expectant management group (12 [6%] vs 51 [27%], odds ratio 0·18, 95% CI 0·08-0·37; p<0·0001). No serious adverse effects associated with the use of a cervical pessary were reported.

INTERPRETATION

Cervical pessary use could prevent preterm birth in a population of appropriately selected at-risk women previously screened for cervical length assessment at the midtrimester scan.

FUNDING

Instituto Carlos III.

Impact of managed clinical networks on NHS specialist neonatal services in England: population based study

OBJECTIVE

To assess the impact of reorganisation of neonatal specialist care services in England after a UK Department of Health report in 2003.

DESIGN

A population-wide observational comparison of outcomes over two epochs, before and after the establishment of managed clinical neonatal networks.

SETTING

Epoch one: 294 maternity and neonatal units in England, Wales, and Northern Ireland, 1 September 1998 to 31 August 2000, as reported by the Confidential Enquiry into Stillbirths and Sudden Deaths in Infancy Project 27/28. Epoch two: 146 neonatal units in England contributing data to the National Neonatal Research Database at the Neonatal Data Analysis Unit, 1 January 2009 to 31 December 2010.

PARTICIPANTS

Babies born at a gestational age of 27(+0)-28(+6) (weeks+days): 3522 live births in epoch one; 2919 babies admitted to a neonatal unit within 28 days of birth in epoch two.

INTERVENTION

The national reorganisation of neonatal services into managed clinical networks.

MAIN OUTCOME MEASURES

The proportion of babies born at hospitals providing the highest volume of neonatal specialist care (≥ 2000 neonatal intensive care days annually), having an acute transfer (within the first 24 hours after birth) and/or a late transfer (between 24 hours and 28 days after birth) to another hospital, assessed by change in distribution of transfer category ("none," "acute," "late"), and babies from multiple births separated by transfer. For acute transfers in epoch two, the level of specialist neonatal care provided at the destination hospital (British Association of Perinatal Medicine criteria).

RESULTS

After reorganisation, there were increases in the proportions of babies born at 27-28 weeks' gestation in hospitals providing the highest volume of neonatal specialist care (18% (631/3495) v 49% (1325/2724); odds ratio 4.30, 95% confidence interval 3.83 to 4.82; P<0.001) and in acute and late postnatal transfers (7% (235) v 12% (360) and 18% (579) v 22% (640), respectively; P<0.001). There was no significant change in the proportion of babies from multiple births separated by transfer (33% (39) v 29% (38); 0.86, 0.50 to 1.46; P=0.57). In epoch two, 32% of acute transfers were to a neonatal unit providing either an equivalent (n=87) or lower (n=26) level of specialist care.

CONCLUSIONS

There is evidence of some improvement in the delivery of neonatal specialist care after reorganisation. The increase in acute transfers in epoch two, in conjunction with the high proportion transferred to a neonatal unit providing an equivalent or lower level of specialist care, and the continued separation of babies from multiple births, are indicative of poor coordination between maternity and neonatal services to facilitate in utero transfer before delivery, and continuing inadequacies in capacity of intensive care cots. Historical data representing epoch one are available only in aggregate form, preventing examination of temporal trends or confounding factors. This limits the extent to which differences between epochs can be attributed to reorganisation and highlights the importance of routine, prospective data collection for evaluation of future health service reorganisations.

Biomarkers of spontaneous preterm birth: an overview of the literature in the last four decades

BACKGROUND

Understanding spontaneous preterm birth ([PTB] < 37 weeks) is difficult due to heterogeneities associated with multitudes of risk factors and pathophysiological pathways. Several biomarkers are routinely used clinically for predicting preterm labor; however, these factors are either nonspecific or detected too late.

OBJECTIVE

Systematic review of literature on PTB biomarkers in the last 40 years to map out the existing knowledge and gaps in understanding PTB biomarkers.

SEARCH STRATEGIES

Five electronic databases were searched for human studies on PTB biomarkers published in any language between 1965 and 2008.

SELECTION CRITERIA

The phenotype of interest for final data extraction was exclusively spontaneous PTB with no rupture of membranes. Data extraction included (a) general characteristics of the study (clinical setting, period, and study design), (b) study/participant characteristics (inclusion and exclusion criteria, race/ethnicity, number of participants, gestational age at sampling, (c) characteristics of the biomarker (type, rationale for its selection, type of biological sample, and assay used, and (d) concentration of biomarkers in cases and controls.

DATA COLLECTION AND ANALYSIS

The search yielded 7255 citations and data were extracted from 217 articles which met our inclusion and exclusion criteria.

MAIN RESULTS

A total of 116 different biomarkers were reported and these were assayed 578 times in the 217 included studies. Over two thirds of the 217 studies were performed on North American or European populations. No reliable biomarkers emerged as a risk predictor of PTB.

CONCLUSIONS

Identifying similar studies on biomarkers for the prediction of PTB was a very challenging task due heterogeneities in study design, sampling issues (types, timing and processing), assay methods, and analyses. Major areas of concern identified in this review include poor phenotype definition, nonideal study designs and poor rationale for biomarker selection and assays and population stratification issues.

Relationship between periodontal diseases and preterm birth: recent epidemiological and biological data

For ten years, the incidence of preterm birth does not decrease in developed countries despite the promotion of public health programs. Many risk factors have been identified including ethnicity, age, tobacco, and infection. However, almost 50% of preterm birth causes remain unknown. The periodontal diseases are highly prevalent inflammatory and infectious diseases of tooth supporting tissues leading to an oral disability. They influence negatively general health worsening cardiovascular diseases and diabetes. Periodontal diseases have been also suspected to increase the rate of preterm birth, but data remain contradictory. The objective of this review is to present the principal results of epidemiological, biological, and interventional studies on the link between periodontal diseases and preterm birth. The conclusions of this work underline the importance for the physician/obstetrician to identify women at risk for preterm birth and to address these patients to dentist for periodontal examination and treatment in order to limit adverse pregnancy outcomes.

Specialised antenatal clinics for women with a pregnancy at high risk of preterm birth (excluding multiple pregnancy) to improve maternal and infant outcomes

BACKGROUND

Amongst the risk factors for preterm birth, previous preterm delivery is a strong predictor. Specialised clinics for women with a history of spontaneous preterm delivery have been advocated as a way of improving outcomes for women and their infants.

OBJECTIVES

To assess using the best available evidence, the value of specialised antenatal clinics for women with a pregnancy at high risk of preterm delivery when compared with 'standard' antenatal clinics.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 June 2011).

SELECTION CRITERIA

All published, unpublished, and ongoing randomised controlled trials (including cluster-randomised trials) examining specialised compared with standard antenatal clinic care for women with a singleton pregnancy considered at high risk of preterm labour.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data.

MAIN RESULTS

We included three trials with 3400 women, all carried out in the USA. All focused on specialised clinics for women at high risk of preterm birth. Gestational age at delivery, preterm delivery, or both were primary outcomes in all studies. The interventions in the three trials differed.Overall there was very little data on our prespecified outcomes. For most outcomes a single study provided data, hence there was not the statistical power to detect any possible differences between groups. There was no clear evidence that specialised antenatal clinics reduce the number of preterm births.

AUTHORS' CONCLUSIONS

Specialised antenatal clinics are now an accepted part of care in many settings, and carrying out further randomised trials may not be possible. Any future research in this area should include psychological outcomes and should focus on which aspects of service provision are preferred by women. Such research could underpin further service development in this area.

Novel biomarkers for the prediction of the spontaneous preterm birth phenotype: a systematic review and meta-analysis

BACKGROUND

Being able to predict preterm birth is important, as it may allow a high-risk population to be selected for future interventional studies and help in understanding the pathways that lead to preterm birth.

OBJECTIVE

To investigate the accuracy of novel biomarkers to predict spontaneous preterm birth in women with singleton pregnancies and no symptoms of preterm labour.

SEARCH STRATEGY

Electronic searches in PubMed, Embase, Cinahl, Lilacs, and Medion, references of retrieved articles, and conference proceedings. No language restrictions were applied.

SELECTION CRITERIA

Observational studies that evaluated the accuracy of biomarkers proposed in the last decade to predict spontaneous preterm birth in asymptomatic women. We excluded studies in which biomarkers were evaluated in women with preterm labour.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data on study characteristics, quality, and accuracy. Data were arranged in 2 × 2 contingency tables and synthesised separately for spontaneous preterm birth before 32, 34, and 37 weeks of gestation. We used bivariate meta-analysis to estimate pooled sensitivities and specificities, and calculated likelihood ratios (LRs).

MAIN RESULTS

A total of 72 studies, including 89,786 women and evaluating 30 novel biomarkers, met the inclusion criteria. Only three biomarkers (proteome profile and prolactin in cervicovaginal fluid, and matrix metalloproteinase-8 in amniotic fluid) had positive LRs > 10. However, each of these biomarkers was evaluated in only one small study. Four biomarkers had a moderate predictive accuracy (interleukin-6 and angiogenin, in amniotic fluid; human chorionic gonadotrophin and phosphorylated insulin-like growth factor binding protein-1, in cervicovaginal fluid). The remaining biomarkers had low predictive accuracies.

CONCLUSIONS

None of the biomarkers evaluated in this review meet the criteria to be considered a clinically useful test to predict spontaneous preterm birth. Further large, prospective cohort studies are needed to evaluate promising biomarkers such as a proteome profile in cervicovaginal fluid.

Fetal fibronectin as a predictor of spontaneous preterm birth: a European perspective

Preterm birth (PTB) is estimated to account for 6-10% of all births worldwide with 13 million PTBs occurring annually and 1 million resulting in death. The diagnosis of spontaneous preterm labor and accurate prediction of preterm delivery is notoriously difficult. Identification of effective risk assessment markers can potentially improve outcomes by enabling targeted therapy while allowing efficient use of resources and avoiding unnecessary interventions. Advances in perinatal medicine have not reduced PTB and effective measures that improve outcome are yet to be established. However, considerable progress has been made in the development of accurate methods (fetal fibronectin and cervical length assessment) to predict PTB in both symptomatic and asymptomatic high-risk women. The excellent negative predictive value of fFN has the ability to facilitate decision-making regarding admission, in utero transfer, administration of antenatal corticosteroids and/or tocolysis and has been shown to be cost-effective. This review describes the European perspective on the use of fFN and describes ongoing European clinical studies, which are appropriately designed with meaningful endpoints, which will undoubtedly facilitate a better understanding of test accuracy and cost-effectiveness within different populations.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Management of premature prelabor rupture of the membranes

Premature prelabor rupture of the fetal membranes affects about 3% of pregnancies. The cause is usually infection, especially at earlier gestations. The prognosis and the risks of delivery are both much worse at earlier gestations. Before viable pregnancy, termination may be offered. Once the fetus is viable, steroids to mature the fetal lungs and antibiotics to reduce infection are the mainstays of treatment. Delivery is recommended in the presence of signs of clear-cut infection at early gestational ages. At later ones, balancing the risks of infection from conservative treatment against the risk of prematurity from delivery is difficult. Published trials to date have not given clear guidance, but a number are ongoing.

Cost-effective standardization of preterm labor evaluation

OBJECTIVE

The purpose of this study was to determine the effect of a standardized evidence-based protocol for preterm labor evaluation on resource use and obstetrics outcomes.

STUDY DESIGN

We conducted a retrospective 12-month observational study of patients with symptoms of preterm labor at the Mayo Clinic. All patients underwent triage evaluation per a standardized protocol with a combination of cervical length measurement with contingent fetal fibronectin assay.

RESULTS

Of 201 patients who underwent evaluation, 3 women delivered within 7 days, and only 1 woman delivered after a negative evaluation. Mean gestational age at evaluation was 29 weeks 1 day, and delivery was at 38 weeks 3 days of gestation, with an average interval of 57.4 days until delivery. The rate of hospital admission was reduced by 56%, compared with the previous year; an estimated annual cost saving was $39,900.

CONCLUSION

Implementation of a standardized protocol for evaluation of preterm labor reduces the rate of unnecessary hospital admissions for observation with consequent significant reduction in expenses.

Elevated levels of decidual insulin-like growth factor binding protein-1 in cervical fluid in early and mid-pregnancy are associated with an increased risk of spontaneous preterm delivery

OBJECTIVE

To study whether elevated levels of decidual insulin-like growth factor binding protein-1 (IGFBP-1) in the cervical fluid of unselected asymptomatic women in early or mid-pregnancy are associated with spontaneous preterm delivery (PTD).

DESIGN

Prospective population-based cohort study.

SETTING

Maternity Clinics, University Central Hospital, Helsinki, Finland.

POPULATION

A total of 5180 unselected pregnant women.

METHODS

Cervical swab samples were collected during the first and second trimester ultrasound screening. The concentration of IGFBP-1 was measured by immunoenzymometric assay, which detects the decidual phosphoisoforms of IGFBP-1 (phIGFBP-1). Concentrations of 10 micrograms/l or more were considered to be elevated.

MAIN OUTCOME MEASURE

Spontaneous PTD. Results In the first trimester, 24.5% of women, and in the mid-second trimester, 20.2% of women, had an elevated cervical fluid phIGFBP-1 level. The rates of spontaneous PTD before 32 and before 37 weeks of gestation were higher in women with an elevated cervical fluid phIGFBP-1 level, compared with women who had cervical phIGFBP-1 of <10 micrograms/l (1.1% versus 0.3% and 5.7% versus 3.2%, respectively). An elevated phIGFBP-1 level in the first trimester was an independent predictor for PTD before 32 and before 37 weeks of gestation, with odds ratios of 3.0 (95% CI 1.3-7.0) and 1.6 (95% CI 1.2-2.3), respectively. Cervical phIGFBP-1 levels of 10 micrograms/l or more in the first trimester predicted PTD before 32 and before 37 weeks of gestation, with sensitivities of 53.8% and 37.0%, respectively. The negative predictive values were 99.7% and 96.8%.

CONCLUSIONS

Elevated cervical fluid phIGFBP-1 levels in the first trimester were associated with an increased risk of spontaneous PTD.

Individual patient data meta-analysis of diagnostic and prognostic studies in obstetrics, gynaecology and reproductive medicine

Background

In clinical practice a diagnosis is based on a combination of clinical history, physical examination and additional diagnostic tests. At present, studies on diagnostic research often report the accuracy of tests without taking into account the information already known from history and examination. Due to this lack of information, together with variations in design and quality of studies, conventional meta-analyses based on these studies will not show the accuracy of the tests in real practice. By using individual patient data (IPD) to perform meta-analyses, the accuracy of tests can be assessed in relation to other patient characteristics and allows the development or evaluation of diagnostic algorithms for individual patients.

In this study we will examine these potential benefits in four clinical diagnostic problems in the field of gynaecology, obstetrics and reproductive medicine.

Methods/design

Based on earlier systematic reviews for each of the four clinical problems, studies are considered for inclusion. The first authors of the included studies will be invited to participate and share their original data. After assessment of validity and completeness the acquired datasets are merged. Based on these data, a series of analyses will be performed, including a systematic comparison of the results of the IPD meta-analysis with those of a conventional meta-analysis, development of multivariable models for clinical history alone and for the combination of history, physical examination and relevant diagnostic tests and development of clinical prediction rules for the individual patients. These will be made accessible for clinicians.

Discussion

The use of IPD meta-analysis will allow evaluating accuracy of diagnostic tests in relation to other relevant information. Ultimately, this could increase the efficiency of the diagnostic work-up, e.g. by reducing the need for invasive tests and/or improving the accuracy of the diagnostic workup. This study will assess whether these benefits of IPD meta-analysis over conventional meta-analysis can be exploited and will provide a framework for future IPD meta-analyses in diagnostic and prognostic research.