Abstract
OBJECTIVE: To assess whether combining estimated fetal weight (EFW) and fetal Doppler ultrasound parameters would provide information to optimize the timing of birth in monochorionic twin pregnancies and prevent adverse perinatal outcomes. STUDY DESIGN: Retrospective multicentre cohort study. SETTING: Three tertiary centres in the UK, Italy and Belgium. POPULATION: 624 monochorionic twin pregnancies managed between 2013 and 2023. METHODS: Univariable and multivariable analyses assessed the association between EFW and Doppler indices taken within 2 weeks of birth. MAIN OUTCOME MEASURES: Stillbirth at any gestation or iatrogenic preterm birth before 34 weeks for suspected fetal compromise. RESULTS: The primary outcome occurred in 143 (22.9%) pregnancies with 70 cases of early PTB for fetal reasons and 73 cases of at least one IUD. Significant associations between biometric and Doppler parameters and adverse perinatal outcomes were found. The best-performing prediction models incorporated EFW discordance and umbilical artery pulsatility index (UA PI) discordance, achieving an AUC of 0.85 (95% CI 0.78-0.91) and EFW discordance and absent or reverse end diastolic flow of UA PI with an AUC of 0.86 (95% CI 0.80-0.92). The model incorporating EFW and UA PI discordance could be applied to the largest proportion of pregnancies and outperformed the currently clinical sFGR classification in predicting adverse outcomes. CONCLUSION: A model incorporating intertwin EFW discordance and UA PI discordance outperforms the current clinical classification for prediction of adverse perinatal outcomes in monochorionic pregnancies. If confirmed by further external validation studies, these findings could contribute to building a tailored risk assessment in these pregnancies.