Risk factors associated with stillbirth and adverse perinatal outcomes in dichorionic twin pregnancies complicated by selective fetal growth restriction: a cohort study

Abstract Objective The main aim of this study was to investigate the perinatal outcomes of dichorionic twin pregnancies complicated by selective fetal growth restriction (sFGR). Design Retrospective cohort study. Setting Tertiary reference centre. Population Dichorionic twin pregnancies complicated by sFGR between 2000 and 2019 in St George's University Hospital. Methods Regression analyses were performed using generalised linear models and mixed‐effects generalised linear models where appropriate to account for pregnancy level dependency in variables. Time to event analyses were performed with mixed‐effects Cox regression models. Main outcome measures Stillbirth, neonatal death or neonatal unit admission with morbidity in one or both twins. Results A total of 102 (of 2431 dichorionic twin pregnancies) pregnancies complicated by sFGR were included in the study. The Cochrane–Armitage test revealed a significant trend for increased adverse perinatal outcome rates with more severe forms of umbilical artery flow impedance, i.e. reversed, absent, positive with resistant flow and positive flow without resistance. A multivariable model including maternal and conception characteristics had poor predictive accuracy for stillbirth (area under the curve: 0.68, 95% confidence interval [CI] 0.55–0.81) and composite adverse perinatal outcomes (area under the curve: 0.58, 95% CI 0.47–0.70). When umbilical artery Doppler parameters were added to the models, the area under the curve values improved to 0.95 (95% CI 0.89–0.99) and 0.83 (95% CI 0.73–0.92) for stillbirth and composite adverse perinatal outcomes, respectively. Conclusion In dichorionic twin pregnancies complicated by sFGR, the umbilical artery Z ‐scores were associated with both intrauterine death and adverse perinatal outcomes.