title: Prediction of growth discordance in twins with the use of abdominal circumference ratios.
abstract: OBJECTIVE
  The purpose of this study was to assess the accuracy of sonographic prediction of twin birth weight discordance using the abdominal circumference ratio.
  
  
  METHODS
  This was a prospective cohort of diamniotic twin gestations that underwent serial ultrasound examinations every 2 to 4 weeks from 11 to 38 weeks of gestation. Birth weight discordance was defined as > or =25% difference in birth weight, relative to the larger twin. The sensitivity, specificity, and predictive values for the abdominal circumference ratio were assessed for the prediction of growth discordance.
  
  
  RESULTS
  Of 503 diamniotic twin pregnancies, 64 pregnancies (12.7%) had discordant fetal growth. The abdominal circumference ratio could be measured consistently throughout gestation in 100% of twin pairs. Receiver operating curve analysis showed that the abdominal circumference ratio was a good predictor of birth weight discordance (area under the curve = 0.80). An abdominal circumference ratio cutoff of 0.93 yielded a sensitivity and specificity of 61% and 84%, respectively.
  
  
  CONCLUSIONS
  Twin birth weight discordance may be predicted at any gestational age with an abdominal circumference ratio <0.93.
authors.affiliation: Department of Obstetrics and Gynecology, Hôpital Sainte-Justine, Université De Montréal, Québec, Canada.
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Klam
authors.forename: Denyse
authors.initials: D
authors.lastname: Rinfret
authors.forename: Line
authors.initials: L
authors.lastname: Leduc
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging; D001724:Birth Weight; D015331:Cohort Studies; D005260:Female; D005317:Fetal Growth Retardation / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000453:epidemiology; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D011237:Predictive Value of Tests; D011247:Pregnancy; D011446:Prospective Studies; D011792:Quebec / Q000453:epidemiology; D012372:ROC Curve; D012680:Sensitivity and Specificity; D014427:Twins; D016216:Ultrasonography, Prenatal