title: Second-trimester discordance and adverse perinatal outcome in twins: the STORK multiple pregnancy cohort.
abstract: OBJECTIVE
  The aim of this study was to determine the association between biometry discordance at the time of the anomaly scan and adverse perinatal outcomes in twin pregnancies.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Nine hospitals in the Southwest Thames Region of London Obstetric Research Collaborative (STORK).
  
  
  METHODS
  Population multicentre retrospective study of all twin pregnancies booked for antenatal care in nine hospitals over a period of 10 years. Methods Logistic regression and receiver operating characteristic (ROC) curve analyses were performed to evaluate the association between abdominal circumference (AC) and estimated fetal weight (EFW) discordance, recorded between 20 and 22 weeks of gestation, and adverse pregnancy outcomes.
  
  
  METHODS
  Stillbirth, neonatal mortality, preterm birth (PTB) at <34 weeks of gestation, and birthweight (BW) discordance ≥25%.
  
  
  RESULTS
  A total of 2399 twin pregnancies [457 monochorionic (MC) and 1942 dichorionic (DC)] were included in the study. The predictive accuracy of the EFW discordance was poor for fetal loss after 22 weeks of gestation (area under the curve, AUC 0.54, 95% CI 0.46-0.64), fetal loss beyond 28 weeks of gestation (AUC 0.42, 95% CI 0.31-0.52), perinatal loss (AUC 0.51, 95% CI 0.44-0.57), BW discordance (AUC 0.63, 95% CI 0.56-0.65), and PTB before 34 weeks of gestation (AUC 0.52, 95% CI 0.49-0.55). There was no significant difference in the prediction of these outcomes when using EFW discordance or AC discordance.
  
  
  CONCLUSIONS
  Once structural malformations, chromosomal abnormalities, and twin-to-twin transfusion syndrome have been excluded, second-trimester EFW and AC discordance have poor predictive value for adverse perinatal outcomes in twin pregnancy.
authors.affiliation: Fetal Medicine Unit, Division of Developmental Sciences, St George's, University of London, London, UK.
authors.forename: F
authors.initials: F
authors.lastname: D'Antonio
authors.forename: A
authors.initials: A
authors.lastname: Khalil
authors.forename: B
authors.initials: B
authors.lastname: Thilaganathan
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging / Q000196:embryology*; D015331:Cohort Studies; D005260:Female; D020567:Fetal Weight; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D016015:Logistic Models; D008131:London / Q000453:epidemiology; D011237:Predictive Value of Tests; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D059285:Pregnancy, Twin; D047928:Premature Birth / Q000453:epidemiology / Q000209:etiology*; D012372:ROC Curve; D012189:Retrospective Studies; D012307:Risk Factors; D050497:Stillbirth / Q000453:epidemiology; D016216:Ultrasonography, Prenatal
keywords: Pregnancy outcome; second trimester; twin pregnancies; weight discordance