Objective: To evaluate the role of intertwin differences in umbilical artery (UA) pulsatility index (DUAPI) in predicting infant survival in twin-to-twin transfusion syndrome (TTTS) Design: Retrospective cohort study Setting: Baylor College of Medicine, Texas Children’s Hospital and University of Maryland School of Medicine Population: Women who underwent laser surgery due to TTTS between 2002 and 2018. Methods: Absolute DUAPI were calculated prior to laser surgery. ROC analysis was done to derive a DUAPI cutoff value of 0.4 for the prediction of double infant survival. Regression analyses were performed to evaluate the association of DUAPI <0.4 and infant survival in the whole cohort, in TTTS cases with Quintero stages I/II and in those with Quintero stage III/IV; adjustments for gestational age at delivery, Quintero stage, selective fetal growth restriction (sFGR) and other confounders were done. Main Outcome Measure: Double infant survival to 30 days of life Results: 349 TTTS cases were included. Double twin survival to 30 days was observed in 67% (234/349) of cases. Intertwin DUAPI <0.4 was associated with increased double twin survival in the whole cohort (aOR: 3.40; 95% CI: 2.02-5.70; p<0.001), in women with TTTS Quintero stage I or II (aOR: 3.05; 95% CI: 1.32-7.09; p=0.009) and in women with TTTS Quintero stage III or IV (aOR: 3.23; 95% CI: 1.52-8.85; p=0.002). Neither Quintero stage nor sFGR were associated with infant survival. Conclusions: Intertwin differences in UA pulsatility index supersede the Quintero classification in the prediction of double infant survival following laser surgery in TTTS cases.