Second-trimester discordance and adverse perinatal outcome in twins: the STORK multiple pregnancy cohort

ObjectiveThe 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.DesignRetrospective cohort study.SettingNine hospitals in the Southwest Thames Region of London Obstetric Research Collaborative (STORK).Population or samplePopulation 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 22weeks of gestation, and adverse pregnancy outcomes.Main outcome measuresStillbirth, neonatal mortality, preterm birth (PTB) at <34weeks of gestation, and birthweight (BW) discordance 25%.ResultsA 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 22weeks of gestation (area under the curve, AUC0.54, 95%CI 0.46-0.64), fetal loss beyond 28weeks of gestation (AUC0.42, 95%CI 0.31-0.52), perinatal loss (AUC0.51, 95%CI 0.44-0.57), BW discordance (AUC0.63, 95%CI 0.56-0.65), and PTB before 34weeks of gestation (AUC0.52, 95%CI 0.49-0.55). There was no significant difference in the prediction of these outcomes when using EFW discordance or AC discordance.ConclusionsOnce 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.