Prediction of spontaneous preterm birth: no good test for predicting a spontaneous preterm birth.

PURPOSE OF REVIEW: Spontaneous preterm birth complicates 3-11% of pregnancies and is a major cause of neonatal mortality and morbidity worldwide. If accurate tests can be identified, a potentially effective screening strategy with an adjunct preventive therapy may be trialled to reduce the rate of spontaneous preterm birth or effective measures be deployed at an early stage of a suspected spontaneous preterm labour before the onset of cervical changes to ameliorate prematurity complications. RECENT FINDINGS: There are many tests predicting spontaneous preterm births, published in the literature individually or in a systematic review. The information has not been collated about all candidate tests simultaneously in a systematic review incorporating a framework on how these tests may be evaluated, modelled with an intervention to provide a number needed to treat and test to inform decision-making. SUMMARY: There were 319 studies evaluating 22 tests. There are many promising tests, for example, history of previous spontaneous preterm birth, cervicovaginal swabs for markers such as fibronectin or HCG, cervical ultrasound, serum CRP and amniotic fluid interleukins for predicting spontaneous preterm birth, but none have exceptional accuracy and the quality of studies was generally poor. Some tests were able to achieve high LR+, but at the expense of LR-, that is, tests good for ruling in disease were poor for ruling out disease and vice versa.

Maternal COVID-19 infection, clinical characteristics, pregnancy, and neonatal outcome: A prospective cohort study.

OBJECTIVE: To study the effect of COVID-19 on pregnancy and neonatal outcomes. STUDY DESIGN: Prospective cohort study in a large tertiary maternity unit within a university hospital with an average annual birth of over 10,000 births. We prospectively collected and analysed data for a cohort of 23 pregnant patients including singleton and multiple pregnancies tested positive for COVID-19 between February 2020 and April 2020 inclusive to assess the effect of COVID-19 on pregnancy, and neonatal outcomes. RESULTS: Twenty-three pregnant patients tested positive for COVID-19, delivering 20 babies including a set of twins, with four ongoing pregnancies at the time of manuscript submission. 16/23 (70 %) whom tested positive were patients from Asian (Indian sub-continent) background. The severity of the symptoms ranged from mild in 13/23 (65.2 %) of the patients, moderate in 2/23 (8.7 %), and severe in 8/23 (34.8 %). Four out of total 23 COVID-19 pregnant patients (17.4 %) developed severe adult respiratory distress syndrome complications requiring ICU support, one of whom led to maternal death 1/23 (4.3 %). 11/23 (48 %) of the patients had pre-existing co-morbidities, with morbid obesity 5/23 (21.7 %) and diabetes 4/23 (17.4 %) being the more commonly represented. Of the 23 pregnant patients 19 were in their third trimester of pregnancy and delivered; 7/19 (36.8 %) had preterm birth, 3/19 (15.8 %) developed adult respiratory distress syndrome before delivery, and 2/19 (10.5 %) had pre-eclampsia. 16/19 (84 %) of patients delivered by C-section. Out of the 20 new-borns, 18 were singletons with a set of twin. CONCLUSION: COVID-19 is associated with high prevalence of preterm birth, preeclampsia, and caesarean section compared to non-COVID pregnancies. COVID-19 infection was not found in the newborns and none developed severe neonatal complications.

Differentiated-type vulval intraepithelial neoplasia has a high-risk association with vulval squamous cell carcinoma.

OBJECTIVE: To assess the potential malignant risk of vulval premalignant conditions, in particular, to investigate whether there is a difference in the cancer risk between women with the 2 types of vulval intraepithelial neoplasia (VIN). METHODS: All vulval biopsy specimens taken for any reason in a single center for a 5-year period were identified. The histologic reports of 1309 biopsy specimens from 802 women were reviewed, and all pathologic conditions present were recorded for each woman. Reports of patients with biopsy specimens containing usual-type VIN, differentiated-type VIN, lichen sclerosus, and squamous hyperplasia were selected and analyzed for the presence of metachronous or subsequent carcinoma to give a proportional risk for each condition. RESULTS: Five hundred eighty women were identified with premalignant vulval conditions: 171 had usual-type VIN, 70 had differentiated-type VIN, 191 had lichen sclerosus, 145 had squamous hyperplasia, and 3 had other conditions not included in this analysis. Within these groups, the numbers of women with prior, synchronous, or subsequent vulval squamous cell carcinoma were 44 (25.7%), 60 (85.7%), 53 (27.7%), and 53 (31.7%), respectively (P = 0.000). CONCLUSIONS: Differentiated-type VIN is significantly more associated with vulval squamous cell carcinoma than usual-type VIN.

An economic evaluation of alternative test-intervention strategies to prevent spontaneous pre-term birth in singleton pregnancies.

OBJECTIVE: To investigate the potential cost-effectiveness of alternative 'test-and-treat' strategies in the prevention of spontaneous pre-term birth before 34 and 37 weeks' gestation. DESIGN: Model-based economic evaluation. Setting. Clinics, general practices, health centers or any setting delivering antenatal care. POPULATION: Asymptomatic women in early pregnancy and symptomatic women with threatened pre-term labor in later pregnancy. METHODS: Data from systematic reviews of effectiveness and accuracy were combined into strategies and analyzed using a decision-tree model. Full deterministic and probabilistic sensitivity analyses were carried out. MAIN OUTCOME MEASURES: Spontaneous pre-term labor avoided for asymptomatic women and spontaneous pre-term birth avoided for symptomatic women. RESULTS: The systematic reviews identified evidence on the accuracy of 22 types of tests and on the effectiveness of 40 possible interventions. Cost data were based on secondary evidence, supplemented with primary data from local sources. Testing prior to intervention was not shown to be the most cost-effective strategy in the main analyses for 34 and 37 weeks. Prophylactic fish oil in asymptomatic women, without prior testing, was highlighted as potentially cost-effective in preventing threatened pre-term labor before 34 weeks. In symptomatic women with a viable pregnancy, indomethacin without prior testing was a potentially cost-effective strategy to prevent pre-term birth occurring before 37 weeks. CONCLUSION: An effective, affordable and safe intervention applied to all mothers without prior testing is likely to be the most cost-effective strategy in the prevention of spontaneous pre-term labor and birth. The results reported in this paper are important for prioritizing future research, world-wide.

Vulval squamous cell carcinoma occurring on a background of differentiated vulval intraepithelial neoplasia is more likely to recur: a review of 154 cases.

OBJECTIVE: To assess the frequency of recurrence of vulval carcinoma, arising from the background of usual-type vulval intraepithelial neoplasia (uVIN), differentiated VIN (dVIN, and nonneoplastic epithelial disorders (NNEDs). STUDY DESIGN: A retrospective review was conducted of 200 pathology specimens of vulval squamous cell carcinoma (VSCC) from 154 women over a 5-year period. The pathologic findings were reviewed where information of the adjacent pathology and number of recurrences of carcinoma for each woman were recorded. The number of recurrences was then correlated with the adjacent pathology using logistical regression analysis. RESULTS: The overall recurrence rate for vulval carcinoma was 22.6%. A single recurrence occurred in 12.9% of patients, whereas 5.8% had 2 recurrences and 3.9% has 3 recurrences of vulval carcinoma. The odds ratio (OR) of having a recurrence of VSCC associated with dVIN alone is 3.85 (95% CI 0.52, 28.24) and 4.3 when associated with dVIN in combination with NNEDs (95% CI 0.84, 21.92), whereas with VSCC associated with uVIN the OR is 1.35 (95% CI 0.20, 9.01). CONCLUSION: Vulval cancers arising on a background of dVIN appear more likely to recur than cancers arising from undifferentiated VIN; this is compounded by the concurrent presence of NNEDs.

Risk screening for spontaneous preterm labour.

Prevention of viable spontaneous preterm birth before 34 weeks' gestation through screening is one of the key aims of antenatal care as birth below this threshold of prematurity has implications for child, mother and society. If women can be identified to be at high risk of spontaneous preterm birth in early pregnancy, they can be targeted for more intensive antenatal surveillance and prophylactic interventions (primary prevention). However, the disease mechanisms behind preterm birth are not well understood. Consequently, tests for its prediction and treatments for its prevention are not well developed. Additionally, no randomised controlled trial focusing on prevention of spontaneous preterm birth related perinatal morbidity and mortality through a screening programme exists. This chapter describes a generic framework for combining screening information with therapeutic effect to delineate its role in a screening programme. We use test-treatment combination of previous history of preterm birth and progestational agents as an example. A decision-making framework is built using: (1) evidence for post-test probabilities; (2) evidence for therapeutic effectiveness; and (3) integration of the two evidences to estimate the effect of the test-treatment combination with numbers needed to treat (NNTs). The NNT to prevent one case of spontaneous preterm birth before 34 weeks' gestation with progesterone is seven in women with a previous history; NNT is 41 in women without a previous history; and it is 28 when previous history was not used to guide a decision about prevention. The proposed framework makes decisions about screening and prevention explicit.

The accuracy of maternal anthropometry measurements as predictor for spontaneous preterm birth--a systematic review.

OBJECTIVE: To assess the accuracy with which antenatal maternal anthropometric measurements predict the risk spontaneous preterm birth. STUDY DESIGN: (1) DATA SOURCES: Studies were identified without language restrictions from MEDLINE, EMBASE, PASCAL, BIOSIS, the Cochrane Library, MEDION, National Research Register, SCISEARCH and Conference Papers, and manual searching of bibliographies of known primary and review articles, and contact with authors. (2) STUDY SELECTION AND DATA EXTRACTION: Studies were selected if they used antenatal maternal anthropometric features (pre-pregnancy weight, maternal pregnancy weight gain and maternal height) to predict spontaneous preterm birth. Two reviewers independently selected studies and extracted data on their characteristics, quality and accuracy. Accuracy data were used to form 2 x 2 contingency tables of the maternal anthropometric test results with spontaneous preterm birth as the reference standard. (3) DATA SYNTHESIS: Heterogeneity assessments were carried out to aid the decision regarding pooling of the accuracy results. Likelihood ratios for positive (LR+) and negative (LR-) test results were calculated, and summary estimates were produced in absence of heterogeneity of the accuracy results. RESULTS: There were eight primary accuracy articles that met the selection criteria, which included a total of 122,647 asymptomatic women. There were six studies on pre-pregnancy weight where five measured the body mass index (BMI) and one used an arbitrary measure. There were four studies on the adequacy of pregnancy weight gain and two studies on maternal height as a predictor for the risk of preterm birth. One article contributed three studies, while two articles provided two studies each. The commonest reference standard used was birth before 37 weeks' gestation. None of the studies fulfilled the ideal test accuracy study criteria. There was heterogeneity in the accuracy results of pre-pregnancy BMI but not in the adequacy of weight gain. All three maternal anthropometric features were poor predictors of preterm labour. Pre-pregnancy BMI is a poor predictor of preterm birth before 37 weeks' gestation (LR+ that ranged from 0.96 (95% confidence interval (CI) 0.66-1.40) to 1.75 (95% CI 1.33-2.31)) as are the adequacy of pregnancy weight gain (summary LR+ of 1.81, 95% CI 1.45-2.30) and short maternal height (LR+ of 1.79 (95% CI 1.27-2.52). CONCLUSION: Routine antenatal maternal anthropometric measurements are not useful in predicting the risk of preterm birth before 37 weeks' gestation. Further studies should address their use in combination with other test but need to use a more clinically appropriate reference standard of preterm birth, such as birth before 32-34 weeks' gestation, and improve on the quality of study design.

Aspirin for prevention of preeclampsia in women with historical risk factors: a systematic review.

OBJECTIVE: To examine the effectiveness of aspirin in preventing perinatal death and preeclampsia in women with predisposing historical risk factors, such as previous history of preeclampsia, chronic hypertension, diabetes, and renal disease. DATA SOURCES: Searches were conductes in Medline, Embase, Cochrane Library, National Research Register, SCISEARCH, AND ISI Conference Proceedings without any language restrictions, using the following medical subject headings and text words: "aspirin," "antiplatelet*," "salicyl*," "acetylsalicyl*," "platelet aggregation inhibitors," "pre-eclamp*," "preeclamp*," and "hypertens*. METHODS OF STUDY SELECTION: We included all randomized trials that evaluated the effectiveness of aspirin compared with placebo or no treatment in women with predisposing historical risk factors and reported clinically relevant perinatal or maternal outcomes. Study selection, quality appraisal, and data extractions were performed independently and in duplicate.We identified 14 relevant trials, including a total of 12,416 women. Meta-analysis showed a significant benefit of aspirin therapy in reducing perinatal death (odds ratio [OR] 0.79, 95% confidence interval [CI] 0.64, 0.96) and preeclampsia (OR 0.86, 95% CI 0.76, 0.96). Aspirin was also associated with a reduction in rates of spontaneous preterm birth (OR 0.86, 95% CI 0.79, 0.94), and an increase of 215 g in mean birth weight (weighted mean difference 215, 95% CI 90, 341). There was no increase in the risk of placental abruption with aspirin (OR 0.98, 95% CI 0.79, 1.21). Funnel plot analysis indicated that publication and related biases were unlikely (Egger test, P =.84). CONCLUSION: Aspirin reduces the risk of perinatal death and preeclampsia in women with historical risk factors. Given the importance of these outcomes and the safety and low cost of aspirin, aspirin therapy should be considered in women with historical risk factors.

Electronic searching of the literature for systematic reviews of screening and diagnostic tests for preterm birth.

BACKGROUND: Published systematic reviews on prediction of preterm birth have tended to focus on a limited number of tests and their search strategies have often been relatively simple. Evaluation of all available tests in a systemic review will require a broad search strategy. AIM: To describe a case study of electronic searching for a systematic review of accuracy studies evaluating all tests for predicting preterm birth. METHODS: The search strategy, developed to capture literatures concerning all the tests en-masse consisted of formulation of an appropriate combination of search terms, pilot searches to refine the search term combination, selection of relevant databases, and citation retrieval from the refined searches for selection of potentially relevant papers. Electronic searches were carried out on general bibliographic databases (Biosis, Embase, Medline, Pascal and Scisearch), specialised databases (Database of Abstracts of Reviews of Effectiveness, Medion, National Research Register, Cochrane Controlled Trial Register and Cochrane Database of Systematic Reviews). RESULTS: A total of 30076 citations were identified. Of these 8855 (29%) citations were duplications either within a database or across databases. Of the remaining 21221 citations, 3333 were considered potentially relevant to the review after assessment by two reviewers. These citations covered 19 different tests for predicting preterm birth. CONCLUSIONS: This case study suggests that with use of a concerted effort to organise and manage the electronic searching it is feasible to undertake broad searches for systematic reviews with multiple questions.

Reporting of measures of accuracy in systematic reviews of diagnostic literature.

BACKGROUND: There are a variety of ways in which accuracy of clinical tests can be summarised in systematic reviews. Variation in reporting of summary measures has only been assessed in a small survey restricted to meta-analyses of screening studies found in a single database. Therefore, we performed this study to assess the measures of accuracy used for reporting results of primary studies as well as their meta-analysis in systematic reviews of test accuracy studies. METHODS: Relevant reviews on test accuracy were selected from the Database of Abstracts of Reviews of Effectiveness (1994-2000), which electronically searches seven bibliographic databases and manually searches key resources. The structured abstracts of these reviews were screened and information on accuracy measures was extracted from the full texts of 90 relevant reviews, 60 of which used meta-analysis. RESULTS: Sensitivity or specificity was used for reporting the results of primary studies in 65/90 (72%) reviews, predictive values in 26/90 (28%), and likelihood ratios in 20/90 (22%). For meta-analysis, pooled sensitivity or specificity was used in 35/60 (58%) reviews, pooled predictive values in 11/60 (18%), pooled likelihood ratios in 13/60 (22%), and pooled diagnostic odds ratio in 5/60 (8%). Summary ROC was used in 44/60 (73%) of the meta-analyses. There were no significant differences in measures of test accuracy among reviews published earlier (1994-97) and those published later (1998-2000). CONCLUSIONS: There is considerable variation in ways of reporting and summarising results of test accuracy studies in systematic reviews. There is a need for consensus about the best ways of reporting results of test accuracy studies in reviews.

Simultaneous fallopian tube and duodenal serosal ectopic pregnancies from a spontaneous conception: a case report.

OBJECTIVE: To present a case report of two concurrent ectopic pregnancies (EP), in a disparate distal location within abdominal cavity with potential life-threatening consequences. DESIGN: Case report. SETTING: In-patient acute hospital admission. PATIENT(S): A multiparous woman with two children and a previous right tubal pregnancy treated with laparoscopic salpingectomy, who initially presented with an acute abdominal pain and vaginal bleeding suspicious of an EP. Having had the EP confirmed and treated with laparoscopic salpingectomy, she presented again 3 weeks later with acute abdominal pain, whereupon further evaluation an EP was found on the serosal surface of the second part of the duodenum. INTERVENTION(S): Laparoscopy and laparotomy followed by excision of the duodenal EP. MAIN OUTCOME MEASURE(S): Recovery to health and discharge from hospital. RESULT(S): Tissue histologic confirmation of left fallopian tubal EP, duodenal (second part) serosal EP, and return of ß-hCG level <1 IU/L. CONCLUSION(S): Maternal deaths from failure to manage EPs appropriately remain prominent. This case report underscores the importance of vigilance at initial laparoscopic surgery and the need to reconsider the presence of another EP in any subsequent acute presentation within a short time of discharge. A mandatory, postoperative ß-hCG level monitoring following treatment of all EPs would have alerted to an unusual clinical situation.

Rapid tests for group B Streptococcus colonization in laboring women: a systematic review.

OBJECTIVES: We set out to determine the accuracy and rapidity of various intrapartum group B Streptococcus (GBS) colonization tests. STUDY DESIGN: We performed a systematic review of test-accuracy studies, which were identified without language restriction from Medline and Cochrane databases; bibliographies of known primary and review articles; and contact with authors, experts, and manufacturers. Studies were selected if they tested pregnant women intrapartum for GBS colonization and confirmed by "gold-standard" laboratory cultures. Two reviewers independently selected studies and extracted data on their characteristics, quality, and results. Accuracy data were used to form 2 x 2 contingency tables. Heterogeneity was assessed, and LRs for positive and negative test results were pooled in subgroups of studies of various tests. RESULTS: There were 29 test-accuracy studies in 15,691 women, evaluating 6 different tests: polymerase chain reaction (PCR), optical immunoassay (OIA), DNA hybridization, enzyme immunoassay, latex agglutination, and Islam starch medium tests. The methodologic quality of the studies was generally poor. The most accurate was the real-time PCR test, but it was less rapid than OIA test. Real-time PCR took 40 minutes to complete, whereas the OIA took 30 minutes. CONCLUSIONS: Real-time PCR and OIA are candidates for rapid near patient intrapartum GBS testing to determine the need for antibiotic prophylaxis to prevent neonatal GBS disease. Before implementation in practice, a robust technology assessment of their accuracy, acceptability, and cost-effectiveness is required.

Antigen processing and correlation with immunological response in vulval intraepithelial neoplasia--a study of CD1a, CD54 and LN3 expression.

OBJECTIVE: To study the antigen-presenting cells and co-stimulatory factors (HLA class 2 antigen and adhesion molecule) in different grades of vulval intraepithelial neoplasia (VIN). MATERIAL AND METHODS: Forty-five histology specimens were obtained from 21 women who had previously undergone vulval biopsies for VIN and included 12 specimens of VIN I, 5 of VIN II and 28 of VIN III. The CD1a (Langerhans cell/antigen-presenting cell marker) and co-stimulatory factors--HLA Class 2 antigens (LN3) and the adhesion molecule (CD54)--were semi-quantitatively analyzed in all the specimens. Pearson Chi-squared test was used for statistical analysis. RESULTS: CD1a was increased in 11/12 (91.6%) biopsies with VIN I, in 3/5 (60%) of VIN II and in 4/28(14.3%) of VIN III. There was thus an inverse correlation between CD1a and severity of VIN (Pearson Chi-squared = 26.876, P = 0.001). Qualitatively, there was a basal location of CD1a-positive cells in normal epithelium but had a haphazard distribution in both low grade and high grade VIN. There was no statistical significance in the distribution of LN3 and CD54 in different grades of VIN. CONCLUSIONS: This study shows an alteration in the numbers and spatial arrangement of CD1a-positive Langerhans/antigen-presenting cells in different grades of VIN. There is an increase in the number of cells with CD1a expression in low grade VIN and a decrease in the number of these cells in high grade VIN. Reduction in CD1a expression may reflect the inability of the host to mount an adequate immune response due to reduced antigen presentation in high grade VIN.

Elective cervical cerclage for prevention of preterm birth: a systematic review.

BACKGROUND: Elective cervical cerclage has been purported to prevent spontaneous preterm birth. We present a systematic review to determine the effectiveness of cervical cerclage in preventing spontaneous preterm birth before 34 weeks' gestation. METHODS: Searches were conducted in MEDLINE, EMBASE, Cochrane Library, and Science Citation Index to identify randomized trials published between 1966 and 2002. All randomized trials that evaluated the effectiveness of elective cerclage compared with no cerclage in women who were at risk of preterm birth before 34 weeks' gestation were included for analysis. Quality assessment and data extraction were performed in duplicate. RESULTS: There were seven relevant trials, comprising 2354 women. Meta-analysis was inappropriate because of large differences in the quality of the studies. However, in the largest single trial of good quality, cerclage was shown to prevent birth before 34 weeks' gestation. In this single study the reported number to be treated to prevent one additional preterm birth before 34 weeks was 24 women (95% CI: 10-61). The results of other trials were consistent with the finding of the largest trial. Data on complications were sparse and inconclusive. CONCLUSION: Our systematic review shows that elective cervical cerclage has a significant effect in preventing spontaneous preterm birth before 34 weeks' gestation. Further research should focus on identification and quantification of possible complications, and of risk factors and tests that identify high-risk women who would benefit most from cerclage.

Accuracy of cervicovaginal fetal fibronectin test in predicting risk of spontaneous preterm birth: systematic review.

OBJECTIVE: To determine the accuracy with which a cervicovaginal fetal fibronectin test predicts spontaneous preterm birth in women with or without symptoms of preterm labour. DESIGN: Systematic quantitative review of studies of test accuracy. DATA SOURCES: Medline, Embase, PASCAL, Biosis, Cochrane Library, Medion, National Research Register, SCISEARCH, conference papers, manual searching of bibliographies of known primary and review articles, and contact with experts and manufacturer. STUDY SELECTION: Two reviewers independently selected and extracted data on study characteristics, quality, and accuracy. DATA EXTRACTION: Accuracy data were used to form 2x2 contingency tables with spontaneous preterm birth before 34 and 37 weeks' gestation and birth within 7-10 days of testing (for symptomatic pregnant women) as reference standards. Data were pooled to produce summary receiver operating characteristic curves and summary likelihood ratios for positive and negative test results. DATA SYNTHESIS: 64 primary articles were identified, consisting of 28 studies in asymptomatic women and 40 in symptomatic women, with a total of 26 876 women. Among asymptomatic women the best summary likelihood ratio for positive results was 4.01 (95% confidence interval 2.93 to 5.49) for predicting birth before 34 weeks' gestation, with corresponding summary likelihood ratio for negative results of 0.78 (0.72 to 0.84). Among symptomatic women the best summary likelihood ratio for positive results was 5.42 (4.36 to 6.74) for predicting birth within 7-10 days of testing, with corresponding ratio for negative results of 0.25 (0.20 to 0.31). CONCLUSION: Cervicovaginal fetal fibronectin test is most accurate in predicting spontaneous preterm birth within 7-10 days of testing among women with symptoms of threatened preterm birth before advanced cervical dilatation.

The accuracy of various tests for bacterial vaginosis in predicting preterm birth: a systematic review.

OBJECTIVE: To determine the accuracy with which various types of tests for bacterial vaginosis predict spontaneous preterm birth in pregnant women. DATA SOURCES: Studies were identified without language restrictions through nine different databases, and manual searching of bibliographies of known primary and review articles. STUDY SELECTION AND DATA EXTRACTION: There are four different bacterial vaginosis testing methods: Gram staining tests using either Nugent's or Spiegel's criteria, and gas liquid chromatography are laboratory based, and the fourth method uses clinical (Amsel's) criteria to diagnose bacterial vaginosis. Two reviewers independently selected studies and extracted data on their characteristics, quality and accuracy. Accuracy data were used to form 2 x 2 contingency tables of the bacterial vaginosis test results with spontaneous preterm birth as the reference standard. DATA SYNTHESIS: Data on asymptomatic women and women with symptoms of threatened preterm labour were analysed separately. Data were pooled to produce summary estimates of likelihood ratios for positive (LR+) and negative (LR-) test results for the various types of tests. RESULTS: There were 18 primary articles, involving altogether 17,868 women. There was unexplained heterogeneity in the meta-analyses of the accuracy results, which requires caution in their interpretation. Meta-analyses of studies testing asymptomatic women in the second trimester showed that clinical criteria had a LR+ of 0.98 (95% confidence interval 0.59 to 1.6) and a LR- of 1.00 (0.93 to 1.1), Gram staining (Nugent's criteria) had a LR+ of 1.6 (1.4 to 1.9) and a LR- of 0.9 (0.8 to 0.9), and Gram staining (Spiegel's criteria) had a LR+ of 2.4 (1.4 to 4.9) and a LR- of 0.81 (0.64 to 1.0). Among symptomatic women, Gram staining (Spiegel's criteria) had a LR+ of 1.3 (1.0 to 1.6) and LR- of 0.9 (0.7 to 1.0). CONCLUSION: There was a lack of difference in the accuracy of the various bacterial vaginosis tests for predicting preterm birth in both asymptomatic and symptomatic women of threatened preterm labour.