title: Accurate prediction of pregnancy viability by means of a simple scoring system.
abstract: OBJECTIVE
  What is the performance of a simple scoring system to predict whether women will have an ongoing viable intrauterine pregnancy beyond the first trimester?
  
  
  CONCLUSIONS
  A simple scoring system using demographic and initial ultrasound variables accurately predicts pregnancy viability beyond the first trimester with an area under the curve (AUC) in a receiver operating characteristic curve of 0.924 [95% confidence interval (CI) 0.900-0.947] on an independent test set.
  
  
  BACKGROUND
  Individual demographic and ultrasound factors, such as maternal age, vaginal bleeding and gestational sac size, are strong predictors of miscarriage. Previous mathematical models have combined individual risk factors with reasonable performance. A simple scoring system derived from a mathematical model that can be easily implemented in clinical practice has not previously been described for the prediction of ongoing viability.
  
  
  METHODS
  This was a prospective observational study in a single early pregnancy assessment centre during a 9-month period.
  
  
  METHODS
  A cohort of 1881 consecutive women undergoing transvaginal ultrasound scan at a gestational age <84 days were included. Women were excluded if the first trimester outcome was not known. Demographic features, symptoms and ultrasound variables were tested for their influence on ongoing viability. Logistic regression was used to determine the influence on first trimester viability from demographics and symptoms alone, ultrasound findings alone and then from all the variables combined. Each model was developed on a training data set, and a simple scoring system was derived from this. This scoring system was tested on an independent test data set.
  
  
  RESULTS
  The final outcome based on a total of 1435 participants was an ongoing viable pregnancy in 885 (61.7%) and early pregnancy loss in 550 (38.3%) women. The scoring system using significant demographic variables alone (maternal age and amount of bleeding) to predict ongoing viability gave an AUC of 0.724 (95% CI = 0.692-0.756) in the training set and 0.729 (95% CI = 0.684-0.774) in the test set. The scoring system using significant ultrasound variables alone (mean gestation sac diameter, mean yolk sac diameter and the presence of fetal heart beat) gave an AUC of 0.873 (95% CI = 0.850-0.897) and 0.900 (95% CI = 0.871-0.928) in the training and the test sets, respectively. The final scoring system using demographic and ultrasound variables together gave an AUC of 0.901 (95% CI = 0.881-0.920) and 0.924 (CI = 0.900-0.947) in the training and the test sets, respectively. After defining the cut-off at which the sensitivity is 0.90 on the training set, this model performed with a sensitivity of 0.92, specificity of 0.73, positive predictive value of 84.7% and negative predictive value of 85.4% in the test set.
  
  
  CONCLUSIONS
  BMI and smoking variables were a potential omission in the data collection and might further improve the model performance if included. A further limitation is the absence of information on either bleeding or pain in 18% of women. Caution should be exercised before implementation of this scoring system prior to further external validation studies
  
  
  CONCLUSIONS
  This simple scoring system incorporates readily available data that are routinely collected in clinical practice and does not rely on complex data entry. As such it could, unlike most mathematical models, be easily incorporated into normal early pregnancy care, where women may appreciate an individualized calculation of the likelihood of ongoing pregnancy viability.
  
  
  BACKGROUND
  Research by V.V.B. supported by Research Council KUL: GOA MaNet, PFV/10/002 (OPTEC), several PhD/postdoc & fellow grants; IWT: TBM070706-IOTA3, PhD Grants; IBBT; Belgian Federal Science Policy Office: IUAP P7/(DYSCO, `Dynamical systems, control and optimization', 2012-2017). T.B. is supported by the Imperial Healthcare NHS Trust NIHR Biomedical Research Centre.
  
  
  BACKGROUND
  Not applicable.
authors.affiliation: Department of Obstetrics and Gynaecology, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK. ceciliabottomley@gmail.com
authors.forename: Cecilia
authors.initials: C
authors.lastname: Bottomley
authors.forename: Vanya
authors.initials: V
authors.lastname: Van Belle
authors.forename: Emma
authors.initials: E
authors.lastname: Kirk
authors.forename: Sabine
authors.initials: S
authors.lastname: Van Huffel
authors.forename: Dirk
authors.initials: D
authors.lastname: Timmerman
authors.forename: Tom
authors.initials: T
authors.lastname: Bourne
mesh_terms: D000293:Adolescent; D000328:Adult; D001185:Artificial Intelligence; D015331:Cohort Studies; D020964:Embryo Loss / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006801:Humans; D008131:London / Q000453:epidemiology; D008954:Models, Biological; D011247:Pregnancy; D011248:Pregnancy Complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011255:Pregnancy Maintenance; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D012306:Risk; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D016216:Ultrasonography, Prenatal; D055815:Young Adult